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Главная » 2013 » Ноябрь » 27 » Geology of Glacier National Park And the Flathead Region, Northwestern Montana (p2)
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Geology of Glacier National Park And the Flathead Region, Northwestern Montana (p2)
NOMENCLATURE OF THE RANGES

Geographic nomenclature, especially with respect to the mountain ranges, is in a state of confusion in the part of Montana with which this report is concerned. Few official decisions as to these names are available. The following summary cites the various names that have been applied to the mountain units, the history and authorities for use of these, and the limits within which each name appears to have been intended to be applicable. No new names are proposed.

The different mountain ranges described in the present report (pls. 1, 2, 3) collectively constitute a segment of the eastern part of the physiographic province termed "the Northern Rocky Mountains" (Fenneman, 1930). Within the United States his definition has received acceptance in official and general usage except for such modifications in detail as those of Freeman and his coworkers (Freeman and others, 1945, p. 56; Caldwell, 1954, p. 79-87). A different definition was proposed earlier by Daly (1906, p. 17-43), who used "North American Cordillera" as a broad term for the mountains west of the Great Plains and restricted the term "Rocky Mountains" to the ranges east of what he termed "the Rocky Mountain Trench," although he appreciated that other names had been applied to this same assemblage. Daly's Rocky Mountain Trench forms part of the western boundary of the Flathead region of the present report (pl. 3), although it extends north and south (Calkins, 1909, p. 11) far beyond the limits of that region. Daly's restricted use of "Rocky Mountains" as a topographic term is in accord with long-established usage in Canada (Dawson, 1886, p. 5B, 15B, 18B). It is accepted there and has some support in present local usage in the part of Montana south of Glacier National Park. However, it has not received official sanction or general usage in the United States (Fenneman, 1930, 1931, p. 200-203).

Within Glacier National Park the mountains are divided, by official and popular usage into the Lewis Range on the east and the Livingstone Range on the west. Willis (1902, p. 310-11) defined the Lewis Range as rising from the Great Plains in Canada about latitude 49°10' and extending southward to about latitude 46°45' He named it for Captain Meriwether Lewis, who, he said, was in 1806 the first white man to cross the range. According to Willis (1902, p. 312-313) the southernmost peak of the Livingston Range (as he spelled it) is Mount Heavens (now termed "Heavens Peak"), and the range extends northwestward "to its limit, probably in Mount Head, in British Columbia, about latitude 50°25'." The name "Livingstone Range" was first applied to a mountain mass in Canada by a Captain Blackiston, in 1858, and later defined by Dawson (1886, p. 11B, 22B, 80B). According to Daly (1912, p. 27-30) the southern end of the Livingstone Range of Dawson is a few miles north of North Kootenay Pass, which is about 27 miles north of the international boundary (Canadian Surveyor General's Office, 1916). Daly proposed the name Clarke Range as an approximate equivalent of Willis' Livingstone Range. Although he secured approval from Willis for this change, it has not secured recognition in the United States. The United States Board on Geographic Names (1933, p. 456-468) has rendered decisions which correspond in general to those of Willis within Glacier Natural Park but terminate both ranges close to the international boundary. The Board's decision puts the south end of the Livingstone (not Livingston) Range at McDonald Creek; but as Heavens Peak is the major summit next north from that creek, this agrees with Willis' statement. The Board, however, puts the south boundary of the Lewis Range at the south boundary of Glacier National Park, which would be near latitude 47°15' and far north of the southern terminus proposed by Willis (46°45') The Board's decisions pertain primarily to the crests of the ranges and say nothing as to boundaries between the two adjacent ranges. In Glacier National Park the line of demarcation between the Lewis and Livingstone Ranges is commonly taken to pass through Waterton Lake, up the Waterton Valley, over or around Flattop Mountain, thence down McDonald Creek and through McDonald Lake to the Middle Fork of the Flathead River.

The decision of the United States Board on Geographic Names (1933, p. 456) to place the southern border of the Lewis Range at the southern boundary of Glacier National Park leaves the great mass of mountains south of that boundary and east of the Flathead Range without satisfactory designation. Willis' original definition (1902, p. 310-311) would have included this mass in the Lewis Range. Bevan (1929 p. 430, fig. 1) included these mountains in his proposed Lewis and Clark Range, and his suggestion was adopted by Fenton and Fenton in their index map (1937, fig. 1). It has been employed in other geologic publications but has not become familiar to residents of the region. It has the disadvantage that the name Lewis Range is well established, as just noted, for mountains in Glacier National Park, and there is a Clarke or (Clark) Range west of the Lewis Range in southern Alberta, corresponding to the Livingstone Range in the United States. Geographic features in Canada are not shown on any of the maps accompanying the present report.

Another, but less satisfactory, proceeding would be to use Sawtooth Range for the unnamed mountains south of Glacier National Park. This name was originally loosely used by Chapman (1900, p. 154) and has been applied by Deiss (1943a, fig. 2, p. 207; 1943b, fig. 2, p. 1125-1127) to the mountains immediately along the border of the plains from the North Fork of Dearborn River to the South Fork of Two Medicine Creek. As thus defined, the Sawtooth Range of Deiss constitutes a material restriction of the Lewis and Clark Range of Bevan and leaves unnamed the mountains north of the South Fork of Two Medicine Creek and south of Glacier National Park. The name Sawtooth Range, however defined, has received little support from local usage. It has the disadvantage that there are so many Sawtooth Ranges or Mountains in the west with which it might be confused—there is a Sawtooth Ridge in the southern part of the Saypo quadrangle.

In the western part of the Flathead region, the nomenclature of the mountain ranges is comparatively well established. The westernmost of the ranges here, which is bounded on the west by Flathead Valley and Swan River (U. S. Board Geog. Names, p. 732) has long been known as the Swan Range. This range is bounded on the north by the depression occupied by the Flathead River (U. S. Board Geog. Names, p. 732) near Columbia Falls. Its southern end is far beyond the limits of the territory described in the present report. The next range to the east lies between the Middle and South Forks of the Flathead River and is called the Flathead Range on the U. S. Geological Survey's topographic map of the Nyack quadrangle and on other maps. This name, which appears to have support in local usage, is used in the present report. Fenton and Fenton (1937, fig. 1) use the names Swan Range and Flathead Range on their index map, cited above. The term "Flathead Range" as here used should not be confused with the Flathead Mountains, west of Flathead Valley, as used by Daly and others (Daly, pl. 3, 1912; Calkins, 1909, pl. 1. U. S. Board Geog. Names, 1933, p. 303-304). This source of confusion has been removed by a later decision of the Board on Geographic Names (U. S. Dept. Interior, Board on Geographic Names, decisions rendered between July 1, 1941 and June 30, 1943, p. 45) to substitute the name "Salish Mountains" for the mountain mass previously called Flathead Mountains (pl. 3).

DRAINAGE

Most of the Flathead region and the part of Glacier National Park west of the Continental Divide is in the drainage basin of the Flathead River, which in turn is tributary to the Clark Fork of the Columbia River. Most of Glacier National Park east of the Continental Divide drains into Canada through the Waterton, Belly, St. Mary, and Milk Rivers, but an area in its southern part is tributary to Two Medicine Creek. The water of Waterton, Belly, and St. Mary Rivers finally finds its way to Hudson Bay, but both Milk River and Two Medicine Creek are in the drainage basin of the Missouri River. Most of the Flathead region east of the divide drains into the Marias River (east of area shown on pl. 3), although a small area in the southeastern part drains to the Teton River. Both the Marias and the Teton Rivers join the Missouri River northeast of Great Falls in west-central Montana. Thus, while most of the water in the two regions here described is carried toward the Pacific Ocean, a part reaches Hudson Bay, and the rest flows toward the Gulf of Mexico.

Along the western border of Glacier National Park, the part of the Flathead River locally known as the North Fork of the Flathead flows southeast out of Canada until it reaches the Apgar Mountains, it leaves its broad valley, and crosses the mountains, finally entering Flathead Lake. The Middle and South Forks of the Flathead flow northwest until they reach points near the northern ends of the Flathead and Swan Ranges, respectively, and join the main Flathead. To accomplish the juncture, the Middle Fork has to swing west and then southwest, reaching the main stream a few miles from West Glacier, formerly Belton. The Swan River, in the southwest corner of the Flathead region, flows northwest; but, a short distance after entering the area of plate 2, it swings abruptly west and enters Flathead Lake.

West of the Continental Divide most of the tributary streams descend the mountain slopes roughly at right angles to the range crests and the master streams mentioned in the preceding paragraph. Among those that depart from this normal pattern is McDonald Creek, which flows southeast for 10 miles then swings abruptly southwest to join the Middle Fork of the Flathead. Several of the other streams have nearly right-angle bends, mostly in their upper reaches. For example, Nyack Creek in its upper reaches flows northwest and is almost in line with the upper part of McDonald Creek, whereas most of Nyack Creek flows southwest, joining the Middle Fork of the Flathead about 10 miles (air line) above the mouth of McDonald Creek. The headwaters of Nyack Creek are separated from those of Coal and Park Creeks by narrow, locally gently sloping passes. Presumably Surprise Pass at the head of Nyack Creek is so named because its slopes are so gentle that close observation is required to enable the traveler to judge when he has passed from the drainage basin of Nyack Creek into that of Coal Creek, or vice versa.

East of the Continental Divide the drainage pattern is somewhat more irregular, in keeping with the fact that the master streams are smaller and themselves have irregular courses. This is particularly true in Glacier National Park, although even here many of the streams flow at right angles to the range trends. In the part of the Lewis Range southeast of the park boundary, several streams and parts of streams almost parallel the trend of the range. These streams include the upper reaches of the South Fork of Two Medicine Creek, several of the tributaries of South Badger Creek, Muskrat Creek, and others. On the other hand, many of the streams flow northeast, transverse to the trend of the mountains, and some of these cut through major ridges without apparent regard for their presence. North Badger Creek and the North Fork of Birch Creek are among those in this category.

Some idea of the size of the streams west of the Continental Divide can be gained from the following data. At the gaging station at West Glacier (formerly Belton) (NE1/4, sec. 34, T. 32 N., R. 19 W.), the Middle Fork of the Flathead has a drainage area of 1,140 square miles and an average discharge of 2,492 second-feet and in the water-year 1948-49 had a runoff of 2,695,000 acre-feet. In the calendar year 1948 at the gaging station in the NE1/4 sec. 17, T. 30 N., R. 19 W., the South Fork of the Flathead had a drainage area of 1,640 square miles, an average discharge of 3,110 second-feet and a runoff of 2,779,000 acre-feet (U. S. Geol. Survey, 1952, p. 274). The main Flathead River at Columbia Falls has a drainage area of 4,464 square miles and, before Hungry Horse reservoir was in operation, had an average discharge of 8,687 second-feet. In calendar year 1947, a wet year, it had a runoff of 8,512,000 acre-feet (U. S. Geol. Survey, 1951, p. 255), whereas in calendar year 1948 the runoff was 7,501,000 acre-feet (U. S. Geol. Survey, 1952, p. 266-274). In calendar year 1954 the adjusted runoff was 9,421,000 acre-feet (U. S. Geol. Survey, 1955, p. 213).

The valley of the Middle Fork is much narrower than that of the South Fork. From the gaging stations mentioned above to the points where the upper reaches of these two streams enter the region, the channel of the South Fork has an average rise of about 12 feet to the mile, while that of the Middle Fork has a rise of about 33 feet to the mile.

East of the Continental Divide available data on stream flow are incomplete. St. Mary River near Kimball, Alberta, 4 miles north of the international boundary, has a drainage area of 497 square miles and in calendar year 1954 had a runoff of 776,300 acre-feet, which represents most of the runoff from the eastern side of Glacier National Park (U. S. Geol. Survey, 1957, p. 32). Data for the rest of the eastern part of the park and for the streams in the eastern part of the Flathead region are not at hand. Lakes and ponds are numerous in the dissected high plains east of the mountains. In the part of these plains represented on plates 1 and 2, well over 700 of these are mapped, most of which are south of latitude 48°30' N. and fairly close to the mountains. Some of the ponds have been enlarged by dams to provide water for ranches in the vicinity. Most of these reservoirs are very small, but a few are moderately large. Lower Two Medicine Lake, damming of which was completed in 1913, has a usable capacity of 14,000 acre-feet; and Swift Reservoir also known as the Birch Creek Reservoir, was completed in 1915 and has a usable capacity of 30,000 acre-feet (U. S. Geol. Survey, 1949, p. 44, 67-68). Neither of these reservoirs is actually filled to capacity.

RELIEF

Plates 1 and 2 represent parts of the Lewis, Livingstone, Flathead, and Swan Ranges, plus such minor ridges as Firefighter Mountain, Desert Mountain, and Apgar Mountains. East of the Lewis Range proper there are a few isolated peaks such as Chief Mountain and Divide Mountain. The Flathead and Swan Ranges are clearly defined mountain masses whose slopes descend from fairly straight and continuous range crests to major stream valleys on either side. Both are steeper on the southwest than on the northeast flank. Summits in the mapped part of the Swan Range culminate in Mount Aeneas, 7,630 feet, and Big Hawk Mountain, 7,540 feet, with several others nearly as high. Mud Lake, west of the Swan Range, has an altitude of 3,004 feet, the lowest point in the territory described in the present report. Thus, the maximum relief in the mapped part of the range is a little over 4,600 feet. The highest point in the Flathead Range is Great Northern Mountain, 8,700 feet; and Halfmoon Lake, at the northern end of the range, is a little less than 3,200 feet above sea level. Thus, the maximum relief in the Flathead Range is about 5,500 feet.

The other ranges are not quite such conveniently recognizable units, which has contributed to the confusion in the nomenclature of the geographical features commented upon above. In Glacier National Park the division between the Lewis and Livingstone Ranges might well escape a casual observer, who could easily suppose the great mass of mountains to be a single unit. The impressive cliffs arranged with little discernible pattern add to the unity in topographic character. Cliffs comparable to them are not present on a similar scale in the mountains nearby, as can be seen by comparing figs. 1, 22, 23, and 24 with figs. 2, 3, 27, and 28. The broad, relatively low tops of Flattop (pl. 1) and West Flattop Mountains (about 6,800 feet above sea level) and the wide Waterton Valley north of them together do constitute a break between the ranges that is fairly conspicuous to an observer from suitable vantage points, but relatively few park visitors reach such points. The northeast side of the mountains drops off steeply, in part precipitously (fig. 3), to the edge of the Great Plains, which are diversified by several prominent ridges. Farther west a jumbled mass of mountains extends to the series of gentle ridges on the east side of the valley of the Flathead River.

Within this mountain mass the Continental Divide winds southeastward, passing from the Livingstone Range around the north end of Flattop Mountain to the Lewis Range. Altitudes above sea level range from about 3,100 feet near West Glacier to 10,438 feet at the summit of Mount Cleveland. About a dozen peaks in the park attain altitudes in excess of 10,000 feet, and scores are over 8,000 feet high. On the Great Plains nearby, flat ridge tops are over 5,000 feet high, while the mountain buttresses on the east side of the Flathead River have broad, gently inclined crests that rise to similar altitudes. Thus, the relief within the main mountain mass is about 5,000 feet, and the maximum relief in the park is nearly 7,400 feet. As Waterton Lake (altitude 4,186 feet) is not far from Mount Cleveland, the local relief in the northern part of the park is about 6,300 feet. Most of the highest mountains are east of the Continental Divide. A few, notably in the vicinity of Kintla and Agassiz Glaciers, are west of it.

The southern extension of the Lewis Range differs from the part within Glacier National Park in that it is composed of subparallel ridges, many of which are cliffed along their northeastern flanks. As a whole, as figures 1 and 22 and 23 show, these mountains constitute a rather heterogeneous assemblage. However, some of the ridges, such as Slippery Bill Mountain, the elevations north and south of it, and the ridge surmounted by Half Dome Crag, are sufficiently large and distinct that they might be thought of as separate ranges or subranges. All these are bordered by large valleys that, as the principal mountain ranges of the region, trend northwest. The mountain front as seen from the plains to the east is straighter than the corresponding front in Glacier National Park, and fully as impressive. For example, Half Dome Crag rises 8,095 feet above the sea and is only 3 miles from the border of the plains at an altitude of 5,000 feet. This mountain front is far straighter than the Continental Divide, which winds from ridge to ridge some 8-15 miles within the mountain mass. As is the case farther north, many of the higher peaks are east of the divide. These include Mount Patrick Gass, 8,625 feet; Old Man of the Hills (Dupuyer Mountain), 8,237 feet; Family Peak, 8,095 feet; and thers. A few high peaks, such as Bighorn Mountain, 8,199 feet, and Mount Fields, 8,595 feet, are on the Continental Divide, but most of the summits farther west are well under 8,000 feet in altitude
 
Fig1 View northwest from Bennie Hill Lookout in the Heart Butte quadrangle, Flathead region, showing the unsystematic topography characteristic of this part of the southern extension of the Lewis Range. The rocks belong largely to the Hannan limestone
 
RESOURCES

The land within the confines of Glacier National Park is not subject to commercial development except to the extent necessary to care for park visitors. The park presents magnificent scenery and affords protection to wildlife. As almost the whole of the Flathead region, south of the park, is within parts of two national forests, it is to a large extent in a natural state. Until recently, its principal resources of direct utility have been those related to its scenery and wildlife. Just as in the adjacent park, any attempt to appraise the value of the Flathead region to the Nation must take these factors into consideration. Fish and game are still abundant and varied, especially in those parts of the national forests remote from roads. Parts of Glacier National Park and of the Flathead and Lewis and Clark National Forests retain their wilderness character, but roads and airplane landing fields are encroaching on these.

The mountains of both Glacier National Park and the Flathead and Lewis and Clark National Forests serve as gathering grounds for precipitation, largely in the form of snow, which has been an essential source of supply of surface and ground water for the ranches and farms in these lowlands for over 60 years. The conservation work carried out by the Park and Forest Services in the mountains has contributed materially to maintenance of the water supply and, in the national forests especially, has helped to preserve the timber until such time as it may be used. Some grazing of domestic livestock and a little lumbering have been carried out in the forests, but neither has developed into an important industry as yet. The lumbering during 1950 and 1951 along the South Fork of the Flathead was necessitated by the construction of the Hungry Horse Dam. It has resulted in salvaging some valuable timber from the area that is now flooded by the dam. The water stored in Hungry Horse Reservoir is to be used for power and other purposes, and its flow is regulated in such fashion as to control floods, and to be effectively distributed as needed to the surrounding country.

From time to time some interest has been aroused in the possibility of finding oil, coal, copper, and gold. None of these possibilities were studied in any detail during the present investigation, but such data as are at hand are here summarized. So far as can be judged on the basis of existing information, it appears improbable that any of these commodities will be found in quantities of any great significance within the mountainous part of the regions described in the present report.

No new data on oil in the plains were obtained during the present investigation. A well was sunk in 1948 near the mouth of Blackleaf Canyon in sec. 14, T. 27 N., R. 9 W., to a depth of 7,571 feet without penetrating below disturbed and thrust-faulted rocks and without finding oil in significant quantities. The concepts in regard to structure that are outlined later in the present report suggest that similar negative results would be obtained by drilling anywhere within the mountains seen during the present investigation. The band of Cretaceous strata that extends northwestward from the southeast corner of the Marias Pass quadrangle might be more suitable for oil prospecting than other parts of the mountains, but even here deformation has been so intense that it seems unlikely that oil pools of commercial significance have survived, if they ever existed.

The studies here reported on contribute nothing to the problem of possible oil-bearing beds deep in the valley of the Flathead near the Canadian boundary. Erdmann (1947, p. 210-213) has summarized available data on oil and bituminous shale in and near that valley. He mentions reported oil seepages in British Columbia and also near Kintla and Bowman Lakes in Glacier National Park and west of the Flathead River near the mouth of Kishenehn Creek. Test wells in the NW1/4NW1/4NW1/4, sec. 18, T. 37 N., R. 20 W., and in the center of sec. 12, T. 36 N., R. 22 W., were driven in 1902-4, without success. Wells in a nearby area in British Columbia found, according to Erdmann, a little high-gravity oil, but the results were disappointing. Erdmann's summary says that the oil seeps are probably all related to faults regarding which little is known. He says: "Unquestionably oil is present in sufficient amounts to make prospecting intriguing." Some renewal of interest in the British Columbia area has been reported recently.

Erdmann also mentions "cobbles of so-called oil shale" in the gravel along the Flathead River and rumors that deposits have been found in place. He quotes McKenzie's (1916, p. 34-35) description of oil shale in British Columbia and concludes that it is improbable that the reported oil shale along the Flathead in Montana will ever constitute a commercial source of oil.

Coal has long been known to occur in the valleys of the Flathead River and its major forks. The coal is lignitic and occurs in thin beds, and much of it is impure. The best known locality and the one at which most underground work has been done is The Coal Banks in T. 34 N., R. 20 W., on the west side of the Flathead River opposite the ranger station in the same township (pl. 1). Available data on this locality are summarized by Erdmann (1947, p. 207-210). He gives the total production for 1933 at the North Fork mine there (not shown on pl. 1), the only one then producing, as about 600 tons and says that when he visited the mine in September 1934 the daily output was about 10 tons. Kalispell was the principal market although small amounts were sold also in other towns. The road to the mine was usually closed by snow from January to April. More recent data on the operation of this mine are not at hand. The following table, taken from Erdmann's report, will give an idea of the character of the coal. Presumably the sample is fairly representative of the better material in the beds that floor the valleys of the forks of the Flathead. None of the coal beds, individually, appear to be more than a foot or two thick. The beds are separated by bone and clay beds.
 
Lignitic coal beds broadly similar in character to those of the North Fork mine are present along the Middle and South Forks of the Flathead. So far as is known those so far found along the Middle Fork are too thin and impure to have attracted much attention. A little mining has been done along the South Fork, but the deposits are even more remote from good transportation facilities than those along the main river. The abundant timber has furnished the most convenient source of fuel for the few people living along the South Fork, so that there has been little incentive to explore the coal. The known deposits are within the area flooded by the Hungry Horse Reservoir. Erdmann (1944, p. 111-114) says that beds of lignitic coal crop out along the South Fork at several localities. He thinks the coal-bearing zone may be 200-300 feet thick and there may be many thin lenticular seams. The largest seams he saw were 3-6 feet thick. He gives detailed sections of coal-bearing material along the South Fork in the NW1/4 sec. 2, T. 27 N., R. 17 W., and in the southwest corner of sec. 12, T. 27 N., R. 17 W., and says good coal is reported along Wheeler Creek in sec. 14, 15, and 22, T. 27 N., R. 17 W. (In the published report the location was printed as T. 29 N.)

Some prospecting for metalliferous deposits has been carried on both within the present limits of Glacier National Park and south of the park. The work started at a time when the part of the present park east of the Continental Divide was in the Blackfeet Indian Reservation and therefore closed to prospecting by white men (Campbell, 1914, p. 5, 6, 26, 31, 43, 50). About 1890, copper ore was found near the heads of Quartz and Mineral Creeks, both of which are west of the divide. This increased the interest in the region to such an extent that the mountains east of the divide were purchased by the Government for $1.5 million under a treaty approved by the United States Senate on June 10, 1896. The land thus acquired from the Indians was thrown open to mineral entry only about 1898.

Byrne (1901, p. 48-49, 1903, p. 81-82) says that about 100 claims were staked at this time, mostly on two parallel veins associated with the intrusive dikes spoken of as metagabbro in the present report. He says these veins extended from Divide Mountain to Mount Grinnell. This is evidently an error as the metagabbro is confined to the area occupied by the Belt series and the distance between the mountains is much greater than the 10 miles mentioned by Byrne. It would appear that the exploration was concentrated in the area from St. Mary Lake northwest to the vicinity of Mount Grinnell and Ahern Pass, with some work in the valley of Mineral Creek, west of the divide. Metagabbro, both in dikes and in sills, is plentiful in this area. Campbell says the copper deposits are in veins and fracture zones, many of which are on the borders of metagabbro dikes. Byrne, in the two reports just cited, says that most of the claims soon came under the control of two companies and that most of the exploration was by tunnels. A few of the tunnels were several hundred feet long. Byrne speaks optimistically of the showings obtained in 1900 through 1903, but later reports do not mention the district. Campbell also mentions a brief and unsuccessful attempt to mine placer gold near St. Mary. Prospect cuts on fractures containing copper sulfides are visible near the southern tip of Glacier National Park along the lower slopes of Running Rabbit Mountain. The principal result of the mining within the park appears to have been to attract attention to the region, thereby aiding the creation of the national park in 1910.

Some prospecting for metalliferous deposits was carried on in the Flathead region in the past, but as far as known little was found, and there has been almost no activity for some years. According to local report, some gold was found in placer deposits, and possibly also in lodes, but the amounts recovered must have been small. Pits, trenches, and short tunnels were dug on cupriferous lodes in several localities but evidently without sufficient success to encourage continuation of the work.

The excavations of this sort in the Flathead region seen during the present investigation are along Felix Creek near the eastern border of unsurveyed T. 28 N., R. 17 W., and in and near Silver Basin at the head of the South Fork of Logan Creek in the northwestern part of unsurveyed T. 27 N., R. 16 W. The deposits are in irregular and discontinuous fracture and breccia zones in rock of the Belt series. The metallic minerals include pyrite, some chalcopyrite, a little bornite, and abundant chalcocite. The principal gangue mineral is quartz, which appears to have formed in part by replacement and in part by filling of open spaces. Somewhat ferruginous dolomite is also present. So far as can be judged from inspection of material on the dumps, the metal content of the lodes is low.

There are reports that lead ore was mined and packed out some years ago from a prospect in the vicinity of Muskrat Pass in and near the southwestern part of unsurveyed T. 28 N., R. 11 W. This prospect was not found during the present investigation, and no further information is available
 
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