Tritium rainout over the United States in 1962 and 1963

Geological Survey

Abstract ___________________________ 1 Data interpretation _________________ 2 Introduction _______________________ 1 Summary __________________________ 5 Tritium rainout network ____________ 1 References ________________________ 5 Analytical methods _________________ 2

2. Map showing weighted-average tritium coneentration _______________________ 4
3. Map showing total tritium rainout ________________________________________ 4
4. Tritium rainout data for 1963 ____________________________________________ 7 CONTENTS

By G. L. Stewart and C. M. Hoffman

In recent years, because of the similarity of its physical and chemical properties with water, tritiated water (HTO) has proved of great value in water dating and tracer applications. Radioactive isotopes are advantageous as water tracers because they can be detected in relatively small concentrations compared to nonradioactive tracers. Tritium, a radioactive isotope of hydrogen, is probably the best radioactive tracer for water because it is incorporated directly into the water molecule, and its 12.26 years half life permits its use in both short- and relatively long-term experiments.

Small quantities of tritium are produced naturally by cosmic radiation in the atmos - phere. This tritium eventually becomes oxidized, and it is carried to the earth in the form of rain or snow. The tritium production rate is considered to be quite constant and is the basis for water dating, because the tritium concentration in water is proportional to its age. Various estimates of natural tritium activity in precipitation have been made; these range from 2 to 10 TU 1 , the concentration depending upon location with respect to oceanic influences and other meteorologic phenomenon (Kaufman and Libby, 1954, p. 1337; Libby, 1961; Thatcher, 1962).

Since 1952, natural tritium in precipitation has been masked by synthetic tritium placed in the atmosphere by thermonuclear bomb explosions and by nuclear facilities. This synthetic production has resulted in large quantities of tritium being added to the hydrologic environment and has thus produced a tritium pulse valuable for present and future hydrologic investigations.

Since tritium was first introduced as a water tracer (Kaufman and Libby, 1954, p. 1337) in analysis relating to hydrologic problems, several investigations dealing with tritium circulation in the atmosphere and in surface and ground waters have been conducted. In general, these investigations have been quite satisfactory and have further established the potential usefulness of both natural and artificial tritium tracer in hydrologic and meteorologic investigations.

Based upon the premises given above, the U.S. Geological Survey initiated a program in 1958 to measure fluctuating tritium activities in precipitation, which subsequently provides a tag for surface and ground waters. Since that time, precipitation waters have been monitored systematically for tritium activity by the Survey. Initially, three collection stations were established to monitor tritium on a regular basis, and supplemental data for other locations were provided as required. The observation network was expanded to. include 9 stations after the U.S.S.R. broke the 3 -year moratorium and resumed nuclear test - ing in September 1961. To obtain more complete information about tritium rainout patterns and to document tritium data for future work, the network was again revised and expanded in January 1963. It presently includes 15 stations collecting biweekly samples at the following cities: Albuquerque, N. Mex.; Baton Rouge, La.; Bismarck,.N.Dak.; Boston, Mass.; Denver, Colo.; Lincoln, Nebr.; Madison, Wis.; Palmer, Alaska; MenloPark, Calif.; Ocala, Fla.; Portland, Oreg.; St. Louis, Mo.; Salt Lake City, Utah; San Juan, Puerto Rico; and Washington, D.C.

Tritium rainout data reported herein covers a time period from July 1962 to December 31, 1963. These data are almost complete except for a few samples that are missing because of a short discontinuance of sampling during part of July 1962 through March 1963. In March 1963 the station at Albany, N.Y.,was discontinued in favor of a station at Boston, which would be more representative of storms originating in the ocean or along the coast.

Precipitation samples were collected in a standard 8-inch U.S. Weather Bureau rain gage. The total amount of precipitation falling during the collection period was measured in the rain gage at the end of the collection period and recorded on the sample container at the time of collection. The network is operated by U.S. Geological Survey personnel of the various district offices. Each precipitation sample represents a biweekly composite of precipitation for the particular region. Precipitation collected in the rain gage is poured into polyethylene containers and shipped to the U.S. Geological Survey tritium laboratory for analysis.

U.S. Geological Survey tritium rainout data before July 1962 are listed in previous reports (Thatcher, 1962; Thatcher and Hoffman, 1963, p. 5899-5901).

All analytical work was done by the U.S. Geological Survey tritium laboratory in Washington, D.C. Where direct measurement of samples was not feasible, the samples were enriched in electrolysis cells. Most precipitation samples collected during the time period covered in this report were of sufficient tritium activity that electrolytic enrichment was not necessary. In general, higher activity samples were counted directly with a liquid scintillation spectrometer and low activity by a gas-phase counting system employing Geiger-MUUer detectors. Counting and electrolytic enrichment methods, except for a few refinements, are the same as those reported earlier (Hoffman and Stewart, 1966).

The statistical counting error was + 5 percent or less; the maximum probable analytical error was generally less than + 10 percent.

The spring rise and late spring-early summer peak observed in previous years was also characteristic of 1963 precipitation. The two curves on figure 1 are representative of the 1963 tritium rainout pattern. Peak tritium concentrations for areas included in the network were three or more times greater than in 1962. Complete tritium rainout data are not available for 1962 precipitation; therefore, only general comparisons between 1962 and 1963 data can be made. The highest tritium concentration measured for 1963 precipitation waters was 12,950 TU for a sample collected at Denver, Colo. during May 5 18. Salt Lake City, Utah, precipitation for June 2 9 and June 16 30 contained tritium concentrations of 11,450 TU and 10,440TU, respectively. If individual storms had been monitored for tritium activity, peak values would probably be higher than those reported here.

It is the total tritium rainout, calculated by multiplying the tritium concentration by the amount of precipitation, that is of greatest hydrologic significance. This product gives the total rainout of tritium radioactivity for a given time and ground-surface area in the vicinity of the collecting station (that is, 1 Tu-cm per unit times 3.2 x 10~3 pico curies per cm 2 per unit time). For meteorologic interpretations of tritium rainout data, tritium concentration in individual storms is important. Data for tritium rainout during 1963 for the various stations and 1962 data not previously reported are listed in tables 1 and 2. The "TU-cm" column represents the total tritium rainout per cm2 of ground-surface area for the collection period specified. For comparison, the 1963 total rainout is given for each location. Where sample collection was not complete, particularly during parts of January and February for a few stations, estimates of tritium rainout were made. These estimates were based upon available tritium data for the location and trends observed at other stations. Because tritium concentrations in precipitation were low during the time when samples are missing, the error introduced by estimating tritium concentrations and amount of precipitation is insignificant when total 1963 rainout weighted-average tritium concentrations are considered. Precipitation amounts for the missing data and for the Denver, Colo., station were.estimated from Weather Bureau records. All other precipitation amounts were taken directly from rain gage readings at the collection site. Samples from Denver, Colo., were collected at the Denver Federal Center, where precipitation amounts were not recorded but were estimated from Weather Bureau records for the Denver airport about 10 miles away. This introduces an error into computations of total tritium rainout and weighted-average tritium concentration.

The geographic distribution of tritium rainout for 1963 is shown on figures 2 and 3. Because of oceanic influences and other meteorologic phenomena, the tritium concentration in midcontinent precipitation is generally higher than that falling near coastal regions. Weighted-average tritium concentration increases with latitude going from south to north. The relatively low values for total tritium rainout and weighted-average tritium concentrations for Menlo Park are probably due to low rainfall during late spring and early summer when the atmosphere is normally high in tritium. Only 0.08 inch of rain was recorded during May 11 to September 11. Total tritium rainout for Denver and Albuquerque is also lower than expected and is due to low precipitation during the time when tritium in the atmosphere is high. Generally, the data indicate an inverse relationship between the tritium concentration of precipitation and the amount of precipitation. However, biweekly composites were collected, and this generalization does not always hold be cause individual storms were not monitored and the precipitation rate of deposition is important.

Although Portland, Or eg., Bismark, N. D., and Boston, Mass., are at about the same latitude, the total tritium rainout at Bismarck is considerably greater than at the other two locations because oceanic influences are not as great and precipitation patterns are different. The relatively low tritium rainout at Palmer, Alaska, is probably due to oceanic influences.

The primary purpose of this report is to document tritium rainout data and to discuss general observations. Subsequent reports will go into more detail on meteorologic influences causing these observed patterns and the hydrologic implications of tritium rainout.

Locations for 15 sampling stations, collecting biweekly samples for tritium analysis, are listed. Stations in the network were geographically selected to provide representative tritium data for the continental United States, Alaska, and Puerto Rico.

Observations for 1963 tritium rainout are characteristic of previous patterns. A spring rise and late spring-early summer peak was

July 31 __ ____ Aug. 7 14 _ _ ____ Amount precipitation (cm)

2.90 2.16 2.46 Table 1. Iritium rainout data for 1962 Tritium Tritium concenrainout tration (TU-cm) (TU)

Albuquerque, N. Mex. Albany, N. Y.

1,650 observed for all stations, and the total 1963 tritium rainout was considerably higher than it had been in previous years. Peak tritium concentrations were up by a factor of three or more over 1962 reported values. It was also observed that total tritium rainout and weighted-average tritium concentration increase with northern latitude and that midcontinent values are greater than coastal regions where oceanic influences are important. In some places low tritium rainout is related to low precipitation during times when atmospheric tritium is high.

Hoffman, C. M., and Stewart, G. L., 1966, Quantative determination of tritium in natural waters: U.S. Geol. Survey Water-Supply Paper 1696-D (in press). Kaufman, S., and Libby, W. F., 1954, The natural distribution of tritium: Phys. Rev., v. 93, p. 1337. Libby, W. F. } 1961, Tritium geophysics: Recent data and results a symposium in Vienna, Austria, May 3-10, 1961: Tritium in the Phys. and Biol. Sci., v. 1, International Atomic Energy Agency. Thatcher, L. L., 1962, The distribution of tritium fallout in precipitation over North America: Internat. Assoc. Sci. Hydrol. Bull., v. 7, no. 2, p. 48. Thatcher, L. L., and Hoffman, C. M., 1963, Tritium fallout over North America from the Soviet tests in 1961: Jour. Geophys. Research, v. 68, no. 20, p. 5899-5901.

Aug. 29-Sept. 4... Sept. 11-18 ____ Oct. 2-30 ______ Oct. 31-Nov. 28 __ Dec. 4-18 ........ Dec. 19-26 .......

Sept. 30-Oct. 27 .. Nov. 12-Dec. 2 __ Dec. 16-29 ____ .

REFERENCES

Amount precipitation (cm)

5.44 2.11 1.14 Tritium Tritium concenrainout tration (TU-cm) (TU)

1 Qn

Sept. 4_ __ ______ 390 [Items marked with an asterisk (*) indicate no sample collected. Tritium concentration estimated and amount of precipitation taken from Weather Bureau records]

Jan. 1-15___. __ _ Jan. 16-22 ______ Jan. 23-29_______

Mar. 5-18 _______ Mar. 19-30 ______ Apr. 3-11 _______ Apr. 16-May 13 __ May 14 June 12 __ June 13-July 1 ___ July 2-Sept. 2____

Jan. 1 5 ________ Jan. 6-12 __ __ _ Jan. 13-l9_-- Feb. 1-15 ....... Feb. 16-28 ______ Mar. 1-15 ____ _ Mar. 16-31 ______ Apr. 1-15 ____ _ May 15-31 ____ _ June 1-30*___

Jan. 1 Apr. 6 ____ Apr. 7-June 7____ June 8-23 _______ June 24-July 7 ___ July 8-13________ July 22-28_______ July 29-Aug. 11 ._ Aug. 12-25 ___ _

Jan. 1-Feb. 9 ____ Feb. 10-19 ______ Feb. 20-Mar. 3 __ Mar. 4 Aor. 1 ___ Amount precipitation (cm)

.15 .91 .99 Table 2. Tritium rainout data for 1963

Tritium Tritium concenrainout tration (TU-cm) (TU)

Albuquerque, N. Mex.

Baton Rouge, La.

Bismarck, N. D.

1,070 1,350 3.480 Albany, N.Y.

Boston, Mass.

1,230 3.450 Collection period

Jan. 30-Feb. 13 __ Feb. 14-Mar. 4 __

Sept. 3-Oct. 16 __ Oct. 25-Dec. 2___ Dec. 3-31 _______

Total, Albany and Boston __

July 1-15 _______ July 16-31 ______ Aug. 1-15 _______ Aug. 16-22 _ __ __ Aug. 25-Sept. 5 __ Sept. 16-30. _____ Oct. 16-31 ...... Nov. 1-15 ___ __

Aug. 26 Sept. 15. Sept. 16-22______ Sept. 23-29._____ Nov. 4-10 _______ Nov. 25-Dec. 1 __ Dec. 9-15 _______

Apr. 2-15 ___ ___ Apr. 16-29 ______ Apr. 30-May 13 __ Mav 14-28 ______ Amount precipitation (cm)

3.35 1.24 *3.18 2.49 Tritium concentration (TU-cm) (TU)

3,690 4,400 *4,500 6,210 Tritium rainout

12,360 5,460 *14,310 15,460 Aug. 1-15 _______ Aug. 16-31 __ __ _ Sept. 1-15 _______ Sept. 16-30 __ __ _ Oct. 1-15____ ____ Oct. 16-31 ______ Nov. 1 15___ ____ Nov. 16-30 ______ Dec. 1-15 _______ Dec. 16-31 __ __ _ 55.94 3.48 3,510 3,100 9,830 3.17 5.56 2.57 .58 .86 .91 3.-96 .68 .63 4.11 Collection period

Oct. 25-Nov. 1 .... Nov. 2-18 ........ Dec. 1-15 __ __ ..

Jan. 1-12 ........ Jan. 13-Feb. 3____ Feb. 17-24 __ .... Feb. 25-Mar. 3 ... Mar. 10-17_______ Mar. 18-24....... Mar. 25-31....... Apr. 1-14........ Apr. 15-30 ....... May 4-12 ........ June 2 9 _________ June 7-15 ________

Jan. 1-21 . _____ Feb. 4-14 ____ __ Mar. 4-12 ....... Mar. 13-18 ....... Mar. 19-25__ __ __ Apr. 8-15 ........ Apr. 16-23 ___ __ Apr. 24-May 13___ May 14-27________ May 28-nJune 17___ June 18 24 _______ June 25-30 _______

Jan. 1-Feb. 19____ Feb. 20-Mar. 7 ___ Mar. 8-18________ Mar. 25-31__ __ __ Apr. 13-29 ___ ____ May 1-15 ________ May 16-31 _______ June 10-13 _______ June 15-20 _______ July 2-13 ___ __ __ Julv 17-28 _______ Table 2. Tritium raiwout data for 1963 Continued

Amount precipitation (cm)

*1.19 4.60 3.81 5.43 5.03 3'. 81 8.30 5.59 4.24 1.75 1.73 Tritium Tritium concenrainout tration (TU-cm) (TU)

San Juan, Puerto Rico Continued

Salt Lake City, Utah

St. Louis, Mo.

*600 2,940 5,680 3,310 8,450 3,920 21,000 9,390 17,810 1 7?n 1.870 Amount precipi-Collection period tation (cm)

Dec. 16-31 ...__.. 2.36 109.56

June 16-30_______ July 29-Aug. 4 ___ Aug. 5-ll________ Aug. 19-25_______ Aug. 23-^Sept. 8___ Oct. 6-13 ________ Oct. 19-27 _______ Oct. 28-Nov. 10 __ Nov. ll-24_______ Dec. 8-22__ __ ___ Dec. 23-31. __ ...

July 1-15 _ _____ July 16-22 _ ______ July 23-29 _______ July 30-Aug. 5 ___ Aug. 12-19. __ .. Aug. 20-26_______ Sept. 15-30 ______ Oct. 1-7 _________ Oct. 8-^STov. 13 ___ Nov. 26 Dec. 9 ___ Dec. 10-23_______

Aug. 9-l2_____ ___ Aug. 18-29 ______

Nov. 16-30 ___ __ Dec. 7-ll________ Dec. 17-18 __ ___ 0.20 .53 1.37 1.42 2.82 1.04 .94 3.45 2.57 1.57 .71 45.71

1 ^n .20 Tritium concentration (TU-cm) (TU)

7 1 9n 6,610 4,780 5,000 3,260 2,170 1,300 1,700 1,430 1,360

7,630 22,000 10,180 5,600 1 7 3Qn 8,160 1,720 1,380 2,550 1,390 1,000 124,410

6,080 1,260 Amount precipi-Collection period tation (cm)

Jan. 1 Feb. 1 __ . *4.83 Feb. 2-21 ........ Feb. 22-Mar. 9 ... Mar. 10-24....... Mar. 25-Apr. 6 ... Apr. 7-14 ___ ... Apr. 15-30... __ May 1-15 ........ May 16-June 5 ___ 11.22 June 6-July 3_____ Table 2. Tritium rainout data for 1963 Continued

3.30 Tritium Tritium concenrainout tration (TU-cm) (TU)

1,100 2,520 9 1 ^n 1,190

3,150 Washington, D,C.

*2,410 3,620 2,110 9,120 2,790 1,290 1,900 1,510 9,540 10,400 Amount precipi-Collection period tation (cm)

July 4-16.... __ . July 17-Aug. 7 ... Aug. 8-Sept. 10 .. Sept. 11-26 .._... Sept. 27-Oct. 9... Oct. 10-Nov. 15 .. Nov. 16-Dec. 5... Dec. 6-31 ....... 100.51 1.52 3.43 15.75 3.05 4.83 10.80 9.14 8.38 Tritium concentration (TU)

4,800 3,490 1,500 1,730 Tritium rainout (TU-cm)

Geological Survey

Abstract_--___________ 1 Nonmetallic resources _____________ 9 Introduction __________ _ _______ 1 Mica and feldspar -- - -- 9 Summary of geology _________________ 1 Kaolin ______----- -- - 10 Metallic resources _ ___ _______ 3 Asbestos. _ ___ - - - 10 Iron. __ ______ - 3 Road metal - - -- H Titanium _________________________ 4 Sand and gravel ____ - _________ 11 Uranium ___ ____ ___ ______ 5 Building stone _ _ - - H Gold ___________________ 7 Other commodities 12 Zinc and lead _____________________ 1 References.- _______________ 12 Manganesse __ ____ _______ 8 Copper..- __ _ ______ 8

2. Copper content of samples of Montezuma Member of the Grandfather the mineral resources __________________________-----------------_-- 2
3. Sketch of uraninite veinlets at the foot of Bard Falls ___ ____ ___ - ______ 5
4. Map of uranium prospects on North Harper Creek-_____________-------- 6

Linville quadrangle ____________________________________ ___ _________ 8

Mountain Formation i__________________________________________________ 9 CONTENTS

in

By Bruce Bryant and John C. Reed, Jr.

This circular summarizes the information collected on mineral deposits during a study of the Grandfather Mountain window and vicinity in northwestern North Carolina and presents these data independently of the description and interpretation of the general geology of this large and complex area. The Grandfather Mountain area comprises the Linville, Linville Falls, Lenoir, and Blowing Rock 15-minute quadrangles and parts of the Marion 15-minute quadrangel and the Little Switzerland and Marion East T^-minute quadrangles. Geologic information on the area is in published geologic maps (Bryant, 1963, 1965; Reed, 1964a, b) and in the open-file map (Reed and Bryant, 1964). Information in this report pertaining to the Linville and Linville Falls quadrangles has previously been published (Bryant, 1962; Reed, 1964b). The specific localities mentioned in this report can be found on the published quadrangles, for many of the geographic features are too small to be shown on figure 1.

From northwest to southeast the area is composed of the following tectonic units: the Mountain City window, the Blue Ridge thrust sheet, the Grandfather Mountain window, the Brevard fault zone, and the Inner Piedmont (fig. 1).

In the Mountain City window, weakly metamorphosed Lower Cambrian rocks of the Rome Formation, the Shady Dolomite, and the Chilhowee Group are exposed.

The Blue Ridge thrust sheet consists of upper Precambrian schist, gneiss, amphibolite, migmatite, and granitic rock formed during a metamorphic-plutonic event 1,000 1,100 million years ago and intruded by ultramafic rock of early Paleozoic(?) age and leucogranodiorite and pegmatite of early or middle Paleozoic age. These rocks have been metamorphosed one or more times during the Paleozoic. In late Paleozoic time the Blue Ridge thrust sheet moved relatively northwestward at least 35 miles over Precambrian granitic rocks and migmatite and a thick sequence of upper Precambrian sedimentary and volcanic rocks that are now exposed in the Grandfather Mountain window. An intermediate thrust sheet, the Tablerock thrust sheet, occurs above the autochthonous rocks and beneath the Blue Ridge thrust sheet in the southern part of the window. The Tablerock thrust sheet is composed of the Shady Dolomite and rocks of the Chilhowee Group. The rocks in the window and the thrust sheet were pervasively metamorphosed at low grade during the Paleozoic.

The Brevard fault zone, a strike-slip fault of regional extent, truncates the Grandfather Mountain window and the Blue Ridge thrust sheet to the southeast. The fault zone contains slices of exotic rock, and the zone and adjacent rocks showing structural and metamorphic effects related to the faulting form a belt 5 miles wide. Right-lateral movement along the Brevard fault took place in late Paleozoic and early Mesozoic time and may have been closely related to the northwestward transport of the Blue Ridge thrust sheet.

In the inner Piedmont, which is southeast of the Brevard fault, layered biotite and biotite-amphibole gneiss, mica, and sillimanite schist and concordant bodies of cataclastic augen gneiss of Precambrian or early Paleozoic age have been invaded by granitic rocks of early or middle Paleozoic age and by ultramafic rocks of early Paleozoic(?) age. These rocks were subjected to one or more episodes of metamorphism during the Paleozoic.

Historically, iron has been an important mineral resource of the Grandfather Mountain area. A belt of iron prospects and mines in the Linville quadrangle extends northwestward from near Newland through Cranberry and about 6 miles west into Tennessee. The principal producing mine in this belt was the Cranberry mine at Cranberry, N.C.

The first published description of the Cranberry deposit, including several analyses of the ore, was written by Kerr (1875) before any extensive mining had been done. Bayley (1923) gave a rather complete review of the literature on Cranberry mine. During the present survey the underground workings at Cranberry were only partly accessible; most of the description, therefore, is summarized from the literature.

The ore mineral is magnetite; the gangue minerals are, principally, pyroxene, amphibole, epidote, quartz, feldspar, and, subordinately, garnet, and calcite. According to Ross (1935), the country rock contains augite and the ore deposits hedenbergite. Other minerals in the gangue include biotite, pyrite, pyrrhotite, sphalerite, and chalcopyrite. The ore is nontitaniferous and low in phosphorus. The iron content is 30 35 percent.

Keith (1903) recognized that the ore occurs in separate lenses peneconcordant with the foliation of the Cranberry Gneiss; he believed that the ore was postmetamorphic. However, Bayley (1923, p. 67, pi. 4) found that the ore and gangue at the Cranberry deposit were sheared, indicating that the mineralization occurred before or during the latest metamorphism. Goldich and Wedow (1943) considered the ore bodies as discusshaped tectonic lenses. The lenses mined ranged in thickness from a few feet to 200 feet and were as much as 900 feet long. Kline and Ballard (1948, p. 11) referred to an unpublished report by Lucien Easton, which stated that the ore occurs in shoots that strike N. 57° W., dip 30° SW., and are elongate in a S. 70° W., 30° SW., direction of plunge.

Surface float from the Cranberry deposit was mined as early as 1820 (Bayley, 1923, p. 98), but systematic mining did not begin until 1882 when a railroad was completed to Cranberry from Johnson City, Tenn. (Nitze, 1893). In 1884 a small blast furnace capable of handling 40 tons of ore per day was built at Cranberry. After 1900 the ore was shipped to Johnson City where a 100-ton-per-day blast furnace had been built. From 1882 to 1930, about l£ million tons of ore was produced (Kline and Ballard, 1948). During and after World War II the U.S. Bureau of Mines made a geophysical survey of the Cranberry iron belt, did some core drilling, and processed ore in a pilot plant (Kline and Ballard, 1948). Since 1930 the mine has not been operated except during the Bureau of Mines' test, although in recent years some ore has been salvaged from dump material which has been crushed for gravel.

The Cranberry mine was worked by opencut; it was also worked underground on two levels by an adit and slopes from the upper level. The workings underlie an area about 3,700 feet long and 700 feet wide (Kline and Ballard, 1948). Goldich and Wedow (1943) estimated that between450,000and 600,000tons of ore might be taken from the mine by robbing the pillars if the mine were abandoned in the process. They estimated that there might be 1 2 million tons of ore below the present mine workings. Kline and Ballard (1948, p. 85) believed that there are more ore shoots at Cranberry like those already mined, and possibly others elsewhere along the iron-bearing belt.

Other iron prospects in the Cranberry belt in the Grandfather Mountain area have had negligible production, and many are overgrown and difficult to locate. The U.S. Bureau of Mines conducted magnetometer surveys in the Fork Mountain area northwest of Newlandand along a strip from the Cranberry mine to the Tennessee Stateline. One magnetic anomaly was drilled about half a mile west of Elk Park; as much as 44.5 feet of ore having more than 30 percent total iron content over a length of 52.5 feet was found in one hole (Kline and Ballard, 1948), but the other drill holes suggest that ore of that thickness and grade is of limited extent to the depth of 250-440 feet tested.

The origin of the Cranberry deposits is not really known. Keith (1903), who recognized that replacement played an important role in their genesis, attributed the iron-bearing solutions to the Bakersville Gabbro and suggested the Roan Gneiss (his name for the amphibolites) as a possible source of the iron. Bay ley (1923) thought that the iron deposits were formed by intrusion of magmas composed of (1) magnetitic pyroxene pegmatite, (2) pyroxene-magnetite, and (3) magnetite. He also thought that the material of these intr isives originated by differentiation from Precambrian or upper Precambrian mafic magmas.

Megascopic and microscopic textures (Bayley, 1923; Ross, 1935) show that the magnetite and iron-rich silicates replaced the wallrock probably during the plutonic metamorphism when the Cranberry Gneiss was formed because the ore is cut by pegmatite and because both the ore bodies and pegmatite were sheared and partly metamorphosed to low grade along the wallrock. The ore has zones which lack much cataclasis and retrogression. The lenses at. a whole may be largely tectonic in their present distribution and shape. The linear distribution of the mines and prospects in the Linville quadrangle and 6 miles west into Tennessee suggests that their present position is related to Paleozoic tectonism, for they are subparallel with the boundary between rocks of low and medium-grade Paleozoic metamorphism. This boundary may be major thrust fault of Paleozoic age. Neither the distribution nor any possible stratigraphic or tectonic control on the emplacement of the ore deposits before the pervasive shearing is known. Any theory for their origin would be highly specculative. Perhaps the deposits were derived by segregation of iron from amphibolites and schists when those rocks were converted to Cranberry Gneiss during the plutonic metamorphism.

In the northern part of the Linville quadrangle, near Big Ridge, phyllonite zones in Cranberry Gneiss of the Blue Ridge thrust sheet contain magnetite, hematite, and small amounts of sphalerite. Concentrations of hematite with or without magnetite are abundant in phyllonite zones in the Cranberry Gneiss throughout its outcrop area," but they are generally less than 10 feet thick and 100 feet long. Some of the concentrations have been explored.

Hematite is also locally concentrated in phyllonite in the Wilson Creek Gneiss near Tar Ridge in the Blowing Rock quadrangle. We located only one of the four prospects mentioned by Nitze (1893, p. 118-119).

A deposit of ilmenite and magnetite in the Wilson Creek Gneiss near Richlands in the Blowing Rock quadrangle has been known for a long time (Kerr, 1875). Selected ore contained as much as 41.21 percent TiC>2, but the average was 14.90 percent TiO2 and 36.00 percent metallic iron (Nitze, 1893). The deposit was mined from 1942 to 1952 by the Yadkin Valley Ilmenite Co., a subsidiary of the Glidden Co. About 230,000 tons of titanium concentrates was produced.

The ore body consists of a. series of narrow, closely spaced lenses forming a nearly continuous vein which is about 1,000 feet long, and which, as shown by core drilling, extends to a depth of about 200 feet. Mining was discontinued after soft ore near .the surface was removed.

The main part of the mine is an open pit 50-100 feet deep and about 400 feet long. Its bottom is near the level of the Yadkin River. The ore body trended N. 15° E. and dipped 25°-45° SE. The ilmenite and magnetite occur in a gangue of epidote, amphibole, chlorite, biotite, talc, and accessory pyrite. Talc and biotite form segregations. The deposit has sharp contacts with partly layered cataclastic gneiss. The foliation in the gangue material and the enclosing gneiss is parallel. The ore contains concordant wisps of more felsic gneiss 1 inch to 4 feet long and as much as 3 inches thick. Locally, thin stringers rich in ilmenite are found in the wallrock.

In thin section a specimen of gneiss, which was included in the ore and which resembles typical Wilson Creek Gneiss, contains crystals and fragments of crystals of plagioclase altered to albite from the originally coarser grained granitic rock in a matrix of recrystallized albite, quartz, biotite, epidote, and chlorite.

The ore body parallels the regional structural trend of both Paleozoic and Precambrian structural and lithologic elements in this area of the Grandfather Mountain window. The ore apparently replaced the Wilson Creek Gneiss along a linear zone and is younger than the gneiss, which was emplaced 1,000 1,100 million years ago (Davis and others, 1962). The ore has been sheared along with the country rock and is pre-late Plaeozoic in age. The iron and titanium may have been derived from preexisting rock and segregated during the plutonism, but their source is unknown.

A similar, but low-grade, ore body threequarters of a mile to the southeast was reported by Hunter and Gilder sleeve (1946, p. 81). It consists of ilmenite mixed with chlorite and serpentine minerals, and is as much as 25 feet thick and 3/4 mile long.

There was considerable prospecting for uranium in the Grandfather Mountain area in the middle 1950*s, but no minable deposits were found. The areas of greatest activity were in the Wilson Creek Gneiss in the Linville Falls and Linville quadrangles and in the Cranberry Gneiss north of the window in the Linville quadrangle. Radioactive minerals were prospected in (1) heavy mineral partings rich in zircon in the clastic rocks of the Chilhowee Group in the tectonic slices north and west of the window and in arkoses of the Grandfather Mountain Formation within the window; (2) small pegmatites (mostly less than 10 ft in diameter) in Cranberry Gneiss, especially in pegmatites rich in biotite and quartz; and (3) strongly sheared and phyllonitic zones in the Wilson Creek Gneiss.

The most promising of the three occurrences is that in the Wilson Creek Gneiss. The principal prospects were on Ripshin Ridge near North Carolina Highway 181 in the Linville Falls quadrangle, north of the road between Edgemont and Pineola in the Linville quadrangle (the Little Lost Cove prospect), and on and near North Harper Creek at and north of the boundary between the Linville and Linville Falls quadrangles. These prospects were stripped and trenched, and the North Harper Creek deposit was core drilled.

The most abundant uranium minerals occur in scattered uraninite-filled joints in sheared pegmatites in phyllonite zones. The joints commonly dip steeply and strike almost parallel to the regional northwesttrending mineral lineation in the wallrocks. The joints are poorly developed in the surrounding phyllonite and are sparsely mineralized or barren in the phyllonite (fig. 2). Secondary uranium minerals are disseminated in the phyllonites; but their distribution is spotty, and the phyllonite zones themselves are discontinuous.

The following information concerning claims on the Wilson Creek Gneiss is summarized from unpublished data compiled in 1955 and 1956 by S. J. Meliherscik of E. J. Longyear Co.

The uranium-bearing mineral in the phyllonites is torbernite. Selected samples from phyllonites contained as much as 0.28 percent The prospects in phyllonite on Ripshin Ridge and Little Lost Cove were explored by bulldozer cuts. At Ripshin Ridge the radioactive rock was destroyed by the first cut of the bulldozer, and no more could be located in a pit 20 by 100 by 15 feet. Bulldozing at the Little Lost Cove anomalies showed that there the phyllonite lacked horizontal and vertical continuity. The torbernite showings were interpreted as resulting from nearsurface weathering and secondary enrichment of disseminated uraninite.

The best surface showing is at North Harper Creek just below Bard Falls (fig. 3). The average analysis of 6 samples cut at 10-inch intervals across the showing was 1.01 percent UaQj. These samples contained a trace of gold, silver, and ThC>2, and about 0.1 percent copper. Channel and chip samples over a 4-foot width in brecciated granitic rock in Shatley Fork averaged 0.23 percent U^O8. The country rock has a radioactivity 1.5 times background.

In addition to the obvious northwest-trending veinlets, some paper-thin veinlets of uraninite occur on shear planes parallel to the regional structure. Pyrite, pyrrhotite, and chalcopyrite are also found on thin seams parallel to the foliation. Uraninite is also disseminated in a pegmatite about 350 feet downstream from Bard Falls.

Seven holes, totaling 3,055 feet, were drilled inclined steeply to the northwest (fig. 2) in order to intersect the zones of more sheared rock and phyllonite, which are parallel with the regional structural trend. They intersected the pegmatites which occur as tectonic lenses in and parallel to the zones of phyllonite and strongly sheared gneiss and the very thin seams of uraninite which are parallel with the shear planes. However, as the prominent minerals in the surface showings are in veins trending northwest parallel with the drill holes, the principal uranium-bearing structures were not intersected. Ratioactive logging showed only a few anomalies exceeding 0.1 percent U3O&.

Drilling and detailed surface mapping indicated that it was difficult to draw contacts between phyllonite, sheared gneiss, and less sheared granitic rock. These subdivisions are not continuous along strike or downdip.

According to our interpretation, the uranium mineralization occurred during and immediately after the Paleozoic retrogressive metamorphism of the Wilson Creek Gneiss. The high background readings on that rock unit suggest that the showings formed by local mobilization of uranium during the metamorphism and concentration in shear zones in the gneiss and joints in the pegmatities, which formed relatively brittle competent lumps in the shear zones.

A few small gold prospects and mines are found on quartz veins in the rocks of the Inner Piedmont. At the time of our survey these workings were either overgrown or inaccessible. According to Bryson (1936, p. 136), the quartz veins of the South Mountain region, including the southern part of the Grandfather Mountain area, are generally too small to be worked profitably for gold, and no vein in the South Mountain region has ever been worked on a large scale.

Many of the gold prospects are northeast of, and alined parallel to, the northwesttrending diabase dike in the Lenoir quadrangle. However, Nitze and Wilken (1897) reported that the quartz veins in several of the prospects strike N. 50°-60° E. and are 8-10 inches thick, although in the Baker mine the vein strikes N. 35° -45° W. and is 2 5 feet thick. The prospects we saw are in the belt of polymetamorphic rocks adjacent to and southeast of the Brevard fault.

The most recent prospecting has been near the Miller and Scott Hill mines on Celia Creek in the Lenoir quadrangle. There the small growth on the dumps and the state of preservation of the headframe suggest that work has been done since 1936.

Keith (1903) reported that a quartz vein containing gold-bearing pyrite was mined on the north side of Grandfather Mountain in the Grandfather Mountain window in the Linville quadrangle and that similar veins were prospected on the east side of the mountain. Several of these old prospects, at which little or no work has been done in this century, were located in our survey. Most of the prospects are in sericite phyllite and phyllitic siltstone containing quartz veins and lenses and some pyrite. Two prospects are in phyllonitic gneiss on the ridge south of Bellows Creek in the Linville and Blowing Rock quadrangles.

Placer mining has yielded small amounts of gold on the Blue Ridge upland on Howard Creek in the Blowing Rock quadrangle and near Gragg in the Linville quadrangle (Keith, 1903).

Disseminated sphalerite associated with small amounts of cuprite, chalcopyrite, pyrite, and some secondary copper minerals is found in the Shady Dolomite of the Tablerock thrust sheet near Linville caverns in the Linville Falls quadrangle. The ore minerals with quartz and calcite occur in veinlets and irregular replacements in dolomite. One small prospect trench has been opened on the hillside, and in 1943 44, four holes were diamond drilled. No further exploration was done between that time and 1958.

Selected samples from old iron prospects in phyllonite zones in the Cranberry Gneiss on Big Ridge north of Beech Mountain in the Linville quadrangle contain interesting amounts of zinc. The zinc occurs in black sphalerite associated with sericite, magnetite, epidote, albite, fluorite, chlorite, quartz, and accessory apatite and carbonate. No significant amount of copper or lead accompanies the zinc (table 1). A brief examination of surface exposures and the prospects suggest that the sphalerite has a spotty distribution; no minable bodies were seen.

Analysis of a somewhat mineralized graphitic phyllonite, from a graphite prospect south of Dark Ridge Creek in the Cranberry Gneiss lying above the Mountain City window but below the Blue Ridge thrust sheet, revealed 0.1 percent zinc and no unusual amounts of Fb, Cu, or Ni.

Galena reportedly was mined on the ridge where Buckeye Creek turns east to join Beech Creek in the Linville quadrangle (Keith, 1903). A shaft was still visible in 1957, but no lead minerals were found in the phyllonite on the dump.

Galena, in euhedral cubes as much as 5 mm across, and small amounts of chalcopyrite and sphalerite were found in a 25- to 30-foot - thick vein of granular quartz on the north side of Upper Creek in the Linville Falls quadrangle. The vein strikes northeastward parallel to the foliation of the enclosing schist and gneiss of the Piedmont. It is exposed in several prospect pits over a distance of 200 feet; but no recent work has been done, and the pits are slumped and

Table 1 Metal content, in percent, of selected specimens from iron prospects on Big Ridge, Linville quadrangle [Spectrographic analysis by J. C. Hamilton. Results are reported in percent to the nearest number in the series 1, 0.7, 0.5, 0.3, 0.2, 0.15, and 0.1, etc., which represent approximate midpoints of group data on a geometric scale. The assigned group for semiquantitative results will include the quantitative value about 30 percent of the time. M, major constituent, > 10 percent]

Lab.

No.

291880 __ 291881 __ 291882 __ Field Fe No.

G-70-l-b G-70-l-d G-71-l-a 5.0 M M Ti Cu

0.2 0.015 .05 .07 .05 .02 overgrown. Reportedly, the galena carries small quantities of silver.

are widespread in the area, but no specific localities are mentioned. Such reports have a long history, for Elisha Mitchell (1905), who visited the area in 1828, heard them and recorded in his diary: "Such in substance is the account that I received in so many different places and from so many different persons that I am ready to knock down the man who shall tell the tale again."

and ocherous wad occur in alluvial and colluvial clay which caps a small quartzite knob 0.5 mile S. 20° W. of the village of North Cove (formerly Pitts Station) in the Linville Falls quadrangle. The clay contains lenses of gravel. D. A. Brobst (written commun., 1960) estimated that the manganiferous clay is at least 30 feet thick and that it is covered by a soil mantle 5 10 feet thick. Some prospecting and development work was done on the deposit between 1943 and 1950, and several carloads of ore were shipped. All the opencuts and small adits described by Brobst were caved, and the workings were partly overgrown at the time of our visit in 1959.

inches thick are locally found in alluvium and fan deposits.

Mountain Formation contains copper minerals at scattered localities. Malachite is the copper mineral more commonly visible in

0.01 .0015 .0015 Reports of the occurrence of native lead

Botryoidal psilomelane, clayey pyrolusite,

Concentrations of manganese oxides a few

The Montezuma Member of the Grandfather

0.002 .005 .02 Description

Phyllonite containing pyrite. 2.0 Mineralized phyllonite. M Do. Table 2. Copper content of samples of Montezuma Member of the Grandfather Mountain Formation

Lab. no.

hand specimen; it occurs in amygdules, along fractures, and in epidote segregations. Azurite also occurs but is less abundant. No extensive area of mineralized rock of ore grade has yet been found. Analyses (table 2) show that the copper content of the Montezuma Member is very low, even in areas containing visible copper minerals. Several prospects were found in the upper part of the valley of Pigeonroost Creek in the Linville quadrangle.

Both sheet and scrap muscovite has been obtained from the granodiorite pegmatites of the Blue Ridge thrust sheet in the Grandfather Mountain area. Most of the production has come from the southwestern part of the Linville quadrangle and the northwestern part of the Linville Falls quadrangle. This area is part of the Spruce Pine pegmatite district. Most of the productive pegmatites occur in the mica schist and gneiss unit, some in the amphibolite, a few in the granodiorite, and a very few in the unit of mixed rocks. No pegmatites containing commercial muscovite have been found in the Cranberry Gneiss.

Some mica has been produced from pegmatites in mica schist and gneiss north of Boone in the Blowing Rock quadrangle. The prospects near Deep Gap do not appear to have been very productive. A few mica prospects and one mine reportedly are in rocks of the Blue Ridge thrust sheet southeast of the window in the Blowing Rock quadrangle, but we did not visit them.

Various mines in the Grandfather Mountain area have been described (Sterrett, 1923; Kesler and Olson, 1942; Olson, 1944; F. G.

[Determined by colorimetric method by Dwight L. Skinner]

Field no.

RE-71-1 __ AC-14-1 ___ H-5-3-e ___

H-5-5 ____ Outcrop . ... ..

Prospect; no obvious evidence of copper minerals in specimen. Outcrop; evidence of copper mineralization nearby ____.. Cu Source (ppm)

Lesure, written commun., 1964), and the economic geology of the pegmatites has been summarized (Brobst, 1962).

Most of the pegmatites form peneconcordant lenses and pods, the largest a few hundred feet long and several tens of feet thick. Many small ones have been completely removed by mining. Most of the pegmatites lack conspicuous zoning, although a few have quartz cores. The smaller pegmatites have conspicuous cataclastic textures, and their muscovite books are bent and ruled; yet commercial mica has been produced from some foliated pegmatites only a few feet thick. The pegmatites in the Blue Ridge thrust sheet southeast of the window are on the average more strongly deformed than elsewhere, and the largest muscovite we saw there was about 3 inches in diameter.

Scrap mica is obtained as a byproduct of kaolin mining in the northwestern part of the Linville Falls quadrangle.

Feldspar is commonly recovered as a byproduct of the mica mines, but in some mines it is more valuable than the mica. The prospects and small mines in the mixed unit on Bellevue Mountain in the Linville quadrangle appear to have produced only feldspar. These pegmatites are rich in biotite' and poor in muscovite, and the micas are very deformed. A small amount of feldspar has been produced from pegmatites in the Cranberry Gneiss.

The value of sheet mica production fluctuates, depending upon the demand and on the encouragement given by the U.S. Government through its lending and buying policies. For instance, Avery County produced about $186,000 worth of sheet mica in 1958 under Government support (Vallely and others, 1959), but only $9,850 worth in 1962 after support was withdrawn (Beck and others, 1963).

The reserves of sheet mica in the Spruce Pine district probably are at least equal to the production to date, according to Brobst (1962, p. 19).

Kaolin is mined from light-colored muscovite granodiorite saprolite along the north side of Brushy Creek in the northwestern part of the Linville Falls quadrangle. The deposits were opened in 1937, and several large open-pit mines are currently being operated. Scrap muscovite is recovered as a byproduct. Smaller deposits on the north side of Threemile Creek (Parker, 1946), at the west margin of the Linville Falls quadrangle, had not yet been mined in the quadrangle at the time of our mapping (1957).

Twelve samples from the Gusher Knob deposit (just outside the Linville Falls quadrangle north of Threemile Creek) contained an average of about 24 percent quartz, 16 percent mica, 0.5 percent feldspar, 47 percent hydrated halloysite, and 12 percent kaolin (Sand, 1956). The hydrated halloysite is derived from feldspar and the kaolin from muscovite.

The kaolin is as much as 60 feet thick and is overlain in part by terrace gravels averaging 16 feet in thickness and in part by residual soil and stained kaolin averaging 6 feet in thickness (Parker, 1946). The deposits have been formed by deep weathering of the light-colored granodiorite, which almost lacks mafic minerals. The deep weathering took place on broad valley floors, the bottoms of which now stand as gravel-covered terraces as much as 100 feet above the present streams. Commercial kaolin is found as high as 250 feet above Brushy Creek on relatively gently sloping valley sides (Parker, 1946).

Reserves in 1942 were estimated by Parker (1946) to be l| 3 million tons in the Brushy Creek deposits and % l^ million tons in the deposits north of Threemile Creek (Gusher Knob deposits). No records of production or estimates of current reserves are available.

A possible additional source of kaolin in the Grandfather Mountain area is near Deep Gap in the northeast corner of the Blowing Rock quadrangle. The rocks on the gentle slopes near Gap Creek appear to be deeply weathered and to contain numerous bodies of pegmatite and granitic rock, some of which are plagioclase rich and lack mafic minerals. Judged from exposures in the Stony Fork drainage, whatever bodies of kaolin are found would be relatively small compared to those in the Brushy Creek area and would have a width of only several tens of feet.

Small amounts of anthophyllite astfestos have been mined from ultramafic rocks in the Blue Ridge thrust sheet and the Inner Piedmont in the Grandfather Mountain area.

In 1957, just west of Cow Camp Gap in the Linville quadrangle, an ultramafic body 320 feet long and 60 feet wide was being mined for anthophyllite asbestos. The fibers commonly are | 1 inch long, and some are as much as 4 inches. Most are slip fibers and are parallel to the fabric of the rock. Some veins of cross fibers, which are perpendicular to walls of veins, transect the mass; these veins are as much as 2 inches thick. The ultramafic body appears to be concordant with the amphibolite and hornblende gneiss which forms the wallrock. Talc is common at the margin of the body.

Other small ultramafic bodies on the south side of Hawshore Mountain and south of Hughes in the Linville quadrangle have been prospected unsuccessfully for commercial anthophyllite. Asbestos prospects on Snakeden Mountain in the Blowing Rock quadrangle appear to be much older because the pits are overgrown.

The prospect on Camp Branch in the northeastern Blowing Rock quadrangle contains veinlets of asbestiform tremolite with fibers several inches long parallel to the veins and one-fourth inch long perpendicular to the veins.

In the Inner Piedmont one small anthophyllite asbestos mine has been worked northeast of the junction of the Johns River and Wilson Creek in the Lenoir quadrangle. There the asbestos occurs in veins about 1 foot thick in a dunite which has been entirely serpentinized in its interior and converted to talc schist at its margins.

The mines near Cow Camp Gap and the Johns River have been more fully described by Conrad and others (1963, p. 21-22,42-44).

Road metal has been quarried from many different rock units throughout the Grandfather Mountain area. The largest active quarries in 1961 were in the Shady Dolomite at Woodlawn in the Little Switzerland quadrangle and in migmatitic gneiss at the Causby quarry in the southwestern part of the Lenoir quadrangle. The quarry at Woodlawn, which was operated by the State Highway Department, and an inactive one in Shady Dolomite at Ashford were described by Conrad (1960).

Sand and gravel is obtained from stream beds and flood plains at various localities throughout the area. Although many of the operations last only a few months in one place, they have been noted on the quadrangle maps where they were in progress at the time of mapping or had been recently completed.

The coarser grained deposits containing the fewest fragments of weathered rock are found in streams draining quartzite or arkose. Such deposits have been exploited at the head of the Watauga River and along the Linville River just west of the gorge through the Tablerock thrust sheet in the Linville quadrangle (where the deposits are as much as 15 ft thick) and along the Linville River and Paddy Creek in the Linville Falls quadrangle. In the pits on Paddy Creek and the Linville River in the Linville Falls quadrangle, the gravel is poorly sorted and consists of rounded pebbles to boulders of quartzite 1 inch to 3 feet in diameter in a matrix of gray sandy clay. The deposit ranges in thickness from 4 to 10 feet and rests on bedrock. It is overlain by 2 5 feet of gray-yellow or brown sandy clay containing scattered pebbles and cobbles; the clay, in turn, is overlain by brown organic soil.

Most of the larger streams draining the steep southeast-facing margin of the Blue Ridge have considerable fresh sand and gravel in their alluvial deposits. In 1961, gravel operations at the junction of Buffalo Creek with the Yadkin River in the southeast corner of the Blowing Rock quadrangle exposed above water level 6 10 feet of sand, gravel, carbonaceous sand, and clay. Sand is the dominant material. The gravel consists mainly of pebbles and cobbles, and it has a maximum grain size of 1 foot.

Sand is obtained from the bed of the Catawba River near Morgantown.

Plentiful supplies of sand and gravel remain to be exploited on the flood plains of the major streams, such as Wilson Creek, the Johns River, Buffalo Creek, and Elk Creek. In 1962, sand and gravel was probably the most valuable commodity produced in the Grandfather Mountain area. Production for that year was valued at $122,000 in Watauga County and $208,000 in Burke County (Beck and others, 1963).

In the Grandfather Mountain area, building stone is obtained principally from the meta-^ morphosed sedimentary rocks of the Grandfather Mountain window. The most actively worked quarries are in the lowest arkose of the Grandfather Mountain Formation south and east of Grandfather Mountain in the Linville quadrangle. The arkose most used for building is medium grained, light greenish gray, has cleavage parallel with bedding, and is known as "Grandfather Stone." Council (1955) described the quarries on the road between U.S. Highway 221 and Gragg, and also the Green and Taylor quarry east of Linville. Other small quarries are found in the arkose unit north of Foscoe in the Linville quadrangle and north and east of Shulls Mills in the Blowing Rock quadrangle.

Slices of Chilhowee quartzite which are quarried for building stone are along the Linville Falls fault in the Linville Falls quadrangle near North Carolina Highway 181 (Causby and Dula quarries of Council, 1955), on U.S. Highway 221 at the south edge of the Little Switzerland quadrangle (Woodlawn [Teastor] quarry of Council, 1955), and at

Where this page came from

This page was imported from U.S. Geological Survey. Published by the U.S. Geological Survey and, as a work of the United States government, in the public domain.

Nobody has written it yet — it is the source material at a new address, which is why search engines are asked to skip it and why no one earns from it. It is up for grabs: take it on, and it is yours to rewrite and to earn from.