Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/350

322 F³. gradually but steadily east and west towards Mahantango creek and the Juniata river. By reference to the colored map it will be noted that this dividing summit is immediately north of the double anticlinal roll in FlinstoneFlintstone [sic] ridge, which has so duplicated the sandstone and limestone as to present four outcrops of these rocks at this point instead of one. It will be further noted that the Slenderdale anticlinal ridge likewise subsides in both directions from a point north of McAllisterville, carrying down on its expiring anticlinal the Ore sandstone about four miles east, within about a mile of the Monroe township line; and in like manner gradually burying the same measures towards the west just across the Fermanagh township line, where the crest of the anticlinal is indented for about 1½ miles by a small synclinal rolls carrying two interior outcrops of the Ore sandstone just into Fayette township, but being present in the lower Clinton shales as far east as the Lost creek gap.

The geological section in this township extends from the No. II Hudson river slates in the high anticlinal Spiegelmeyer valley of Shade mountain upwards to the Marcellus slate and possibly the lowest bands of the lower Hamilton shale. The map coloring will show the distribution of these and included formations quite as well as any detailed description of them.

The Hudson river slates No. III are exposed along the summit of Shade mountain, where they make a valley about five miles long and half a mile wide between the two opposing Oneida sandstone ridges which flank this valley north and south and rise to elevations of 100′ or 150′ above its level. There are few good exposures of the slate in place, owing both to the natural erosion of these measures, as well as to the large amount of sand débris which is being continually washed down the interior flanks of the ridges into the valley, with the effect of concealing the slate. There is but a single road crossing this high mountain barrier from the Lewistown valley at Adamsburg in Snyder county to McAllisterville in Fayette township.

The Spiegelmyer valley rises to an elevation of about 1000′ feet above Adamsburg and about 900′ above McAllisterville.