The Castle Valley and San Pete Coalfields, Utah.
[From the Report of the U. S. Commissioner of Mining Statistics for 1874.]
THE Castle Valley and San Pete coalfields have attracted considerable attention during the past year, and are, no doubt, of the utmost importance to the lead and silver industries of the Territory; but besides this they are of very great value in connection with the future iron industry of Utah, of the development of which there can be no doubt, in view of the immense iron deposits in a large part of the southern half of the country. In these fields occur coals, which permit of cok-ing. Considering that, besides the beds of Trinidad in Colorado, and one at Mul-len's Pass, Montana, these veins are the only ones known in the far Wes', where large quantities of good coke can be made, their importance for industrial pur-suits is at once apparent.
Mr. J. E. CLAYTON, of Salt Lake City, has kindly furnished me with notes of a late visit to the Castle Valley field, and also with the accompanying ideal sec-tion.
San Pete Trap and Porphyry Valley Wahsatch Range Castle Valley.
The "Castle Valley" coalfield is situated at the eastern base of the Wahsatch range, and 55 miles, by the Gunnison trail, east of "Salina," on the Sevier River. The pass through the mountains by the way of Salt Creek and one of its southern branches, is one of the best for a wagon- or rail-road in any portion of the Wah-satch range.
The formation is sandstone, with two very thick beds of shale or indurated mud. There is but little trace of stratification in these shale beds, but they are cracked into all sorts of irregular shapes. There are occasionally calcareous no-dules imbedded in them, but very few fossils have been found. Mr. CLAYTON found a few Ostreae at the bottom of the upper shale bed, next to the zone of sandstone that contains the principal coil measures, and also found a pavement scale of a shark or ganoid, as well as a petrified trunk of a palm tree, one foot in diameter, and 8 to 10 feet long, the latter imbedded in the sandstone below the upper shale zone. Both the sandstone and shale contain very little lime. The formation is divided into three zones of sandstone, and two of shale, as shown in the section. The lower sandstone was not examined.
The lower shale bed is at least 600 feet thick, and is darker than the upper one, its color along the exposures being dark bluish gray. The upper shale bed is lighter colored on the surface, and dark gray below. The middle sandstone, lying between these two shale beds, is about 800 feet thick, and in this are the great coal seams of Castle Valley. There are from 3 to 5 seams, the two lowest being the most important on account of their size, uniformity, and superior quality. No. 1, the lower bed of coal, is very hard and compact, but little disposed to slack, and in some places along the face of the bluff, where the sandstone stands in perpendicular cliffs, the coal seam shows faces almost flush with the overlying cliffs. The floor of the seam is a hard grayish-white sandstone, made up of clay and sand, for from 2 to 6 feet below the coal, at which point the clay disappears, and the underlying sandstone is yellowish gray, part of it being quite hard and semi-vitreous. The roof is composed of the ordinary gray sandstone of the middle zone. The thickness of seam No. 1 varies from 3 to 8 feet, and will average probably 5 feet of good coal; there is a small seam of black shale near the roof from 1 to 4 inches in thickness. There is no other waste in the bed; a firm sand-stone roof rests immediately on the coal. This coal burns freely with very little smoke, leaves 3 ½ per cent, of white ash, and is remarkably free from sulphur or iron. For the generation of steam, and for domestic use, it has no superior in this country.
No. 2 lies about 40 feet above the one just described, and contains 6 to 20 feet of clean, solid coal, without a seam of shale in it; but there is quite a bed of shale overlying the coal. This overlying shale contains a number of small seams of coal, from 4 inches to 4 feet thick, and is from 20 to 40 feet thick at the point where a cut was made into it. At one point measured, this No. 2 coal-bed was found 21 feet 6 inches thick, and without a trace of shale in it. The floor is like that of No, 1 bed, a white argillaceous sandstone. The quality of the coal is not as good as that of the lower bed; it is softer, more inclined to slack, and has more ash (6 to 10 per cent.), but is also free from sulphur or iron.
Nos. 3 and 4 lie in the upper beds of the middle zone of sandstone. They are not so regular or uniform in size as those described before, but the coal is of the same general quality. These beds vary from 1 to 4 feet in thickness, judging by the exposures examined, except at one or two places where the outcrop is 6 to 8 feet thick.
The principal reason that the upper beds could not be examined as well as the two lower ones, is that they have been burned out over areas of several thousand acres, and several places were found, where they were still burning. The burnt districts could be plainly traced by the color of the sandstone, which is brick-red in these localities.
These overlying coal seams must have been very thick in places, judging from the effects of the lire on the sandstone. There are places, where the latter is not only burnt red, but is actually glazed and vitrified by the heat. Masses of glazed fragments, adhering together in large boulders, can be seen in the side ravines of the main cañons.
The position of these beds is horizontal on a line N. E. and S. W., but in the opposite direction, N. W. and S. E., they lie in gentle waves, making very flat anticlinal and synclinal axes, as shown in the section.
The available area of the coalfields is about sixty square miles. The extent, so far as at present known is 12 miles long N. E. to S. W., by 4 to 8 miles wide from N. W. to S. E.
Nos. 5 and 6 are two well marked coal seams, about 1,200 to 1,500 feet above the middle zone. These beds lie nearly horizontal, showing a slight rise towards the West, but after passing the center of the mountain, the beds all dip in a curved line towards the Sevier River and the San Pete Valley, which is a long narrow valley enclosed between two branches of the Wahsatch range. Along the Eastern side of this valley there is a great fault or break in the formation, and extensive outflows of porphyry, trap, and occasionally true lava, have taken place. The position of the sedimentary beds East of the break is well exposed in Salina Canon, but their positions West of the eruptive rocks can only be inferred by the exposures of the beds West of the valley. The San Pete coal measures are, in Mr. CLAYTON'S opinion, the same as those shown in the mountain section as Nos. 5 and 6. In the prolongation of the Castle Valley section to the West, across Sevier River Valley, the position of large salt deposits, just East of the eruptive rocks, will be remarked; it is readily seen, why this salt was so deposited. The dip of the beds West of the summit of the east range, underlaid by shale, brought the drainage down against the hot eruptive rocks; the water was vaporized and escaped upwards through the crushed and broken shale and the salt crystallized in the interstices of the broken mass. Large deposits of gypsum also occur along the line of fracture near the salt.
To render the Castle Valley coalfields available, a railroad about 85 miles long will be required to connect with the Utah Southern Road at Sevier River Bridge. If the C. P. R. R. Company should build a branch starting from Wells station, or from Tecoma, they would have no obstacles until they reached Salina Canon, a series of low gaps through the Nevada ranges, making the road virtually a valley line from Tecoma to Gunnison's, or Salina Pass, in the East Wahsatch range. From Castle Valley to Denver, to connect with the Kansas Pacific, is the only difficult portion. This line would, however, be 200 miles shorter than the present Pacific lines.
In regard to the San Pete coalfield, I am indebted to Mr. GEO. P. LOCK-WOOD, M. E., of Salt Like City, for the following further information:
The San Pete coal field is located in San Pate Valley, 90 miles south, and 10 miles east, of Salt Lake City. As far as known, it comprises 4,080 acres on the west side of the valley. The sandstone in which the coal is found is estimated to be here 1,500 to 2,000 feet thick. In these rocks five distinct coal veins have been found, which vary in thickness from 8 inches to 4 feet. The two principal veins are respectively 4 feet and 26 inches thick, and are separated by 8 inches of limestone. The strike of the veins is about due N. and S. and they dip at a slight angle to the West. The coal measures are cut by four cañons at right angles to the strike of the veins. Most of the developments are at those points where the veins are exposed on the sides of the cañons.
On the North, in New Cañon, the vein has been opened by 3 working levels—50,100, and 400 feet long respectively. In Old Cañon, on a mile south, there are three levels opened of 50, 200, and 800 feet. In Big Cañon, about two miles further south, there are three openings of a limited depth. The four foot vein has in-creased at this point to five feet. In Axe-handle Canon, about three miles farther south, the vein has been opened and found to be six feet thick, the in-terstratum of limestone having here disappeared. This shows an increasing strength in the vein in going from N. to S. From 2 to 3 miles north of New Cañon, the vein is found near the top of the mountains, while below Axe-handle Cañon it appears in the foot-hills. The 800 foot level at Old Cañon runs north, about parallel with the strike of the vein.
At the heading of this level coal was mined for 20 feet on either side. The roof in this chamber, and in the level is so firm as to need but little support, showing that a minimum amount of coal need be left in the workings as pillars, and wide chambers can be laid out. The coal separates clean from the walls, and the floor is firm and regular. In regard to the estimated amount of coal in these fields, I gather the following from the report of Mr. ISAAC STONE, M E., F. G. S., of North Wales." The length from North to South is about 8 ½ miles, and the width, from 5 to 6 miles; the outcroppings of the coal, at right angles to its strike, looking from the East, may be distinctly traced. From what I saw of the strata underlying the most southern portion of the property, I have no doubt that the same coal will be found there also, making a total length of 8 ½ mile . . . . . . . .The strata, too, parallel with the dip line to the West, can be clearly and distinctly seen, and a definite conclusion may be arrived at as to their continuity westward." Altogether, Mr. STONE estimates the area of the coal fields to be at least 7,760 acres, with an average thickness of fine working coal over the whole area of 3' 6". Future developments may increase the area, as well as strength of vein. It is generally believed that by sinking new veins will be found which would greatly increase the resources of the fields.
The coal is pronounced by H. S. POOLE, F. R. S., of London, Prof. F. A. GENTH, of the University of Pennsylvania, and Mr. STONE, to be bituminous. It is hard, dense, and of uniform structure. Color, black; streak, black; lustre, medium to bright. Specific gravity, undetermined, but low. Cleavage, uniformly parallel to the faces of the cube. Chemical examinations by H. S. POOLE, F. R. S., have shown:
Volatile matter, 35.50 ( includes H. 0.)
Coke 64.50 (" Ash. )
Volatile matter, 33.70 (includes H. 0.)
Fixed Carbon .. 54 29
Ash 12.01 By.
MIDDLE COAL. Vol. matter 32.00 (includes H. 0.)
Fixed Carbon. . 56.80
Average perc'tage of coke 66.13 per cent.
Prof. F. A. GENTH.
Moisture. 1.16 per cent.
Volatile matter 32-91 "
Fixed Carbon 54- 75 "
Ash .11.18 per cent.
Coal contains 2.88 per cent, of Sulphur.
By FRED. CLAUDET, of London
Ash. 10.54 per cent.
Coke 62.10 "
Sulphur 1.80 per cent.
Dr. JOHN PEBCY, London.
Coke 62.00 per cent.
Volatile matter 28.00 "
Ash. . 10 00 per cent.
Dr. GENTH says that "the coking qualities of this coal are not inferior to those of the best Pittsburgh coal, and that the coke made of the same is apparently of excellent quality, and sufficiently dense to bear the burthen of a blast furnace.” Some of the coke, manufactured in a crude way, was used in the blast furnaces of the Germania Works, six miles South of Salt Lake City. When mixed with one-half of St. Louis coke it worked well. Alone, it matted, forming a cake through which the blast could not penetrate. This indicates plainly, that the coal had not been exposed to a sufficient heat, and there is no doubt, that upon a better coking, it would be found suitable, at least, for the use of the lead blast fur-naces, when the charge column is not more than 12 to 20 feet high. Its princi-pal dement now seems to be lack of tenacity. As a steam generator it is claimed that two tons of San Pete coal equal three tons of Wyoming lignite.
The sandstones occurring in the coal measures are of a light gray color. During 1875 it is intended to connect these fields by a narrow gauge road with the Utah Southern R. R., at Nephi, and thus to bring the coal into the market.
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