Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/147

Rh None of the slate valleys marking the positions of the anticlinal axes in the mountain area of the district contain any very great thickness of the No. III measures, and are all much more important in Centre county, where they spread out considerably through the eastern end of Penns Valley. In Union county these slate rocks present no good outcrops, being largely covered with bowlders of the Medina rocks and drift from their decomposition.

The same thing is true of the mountain members as well; for though their presence and extent can be very nearly located by their influence upon the topography of the country, as well as by the immense number of bowlders which their eroded outcrops have given rise to, yet exposures of these rocks in place are extremely rare and are largely confined to a limited area in the southwestern corner of the township, where the erosion of Penns creek and its branches have exposed the white Medina sandstone in the White mountain sub-division of Jack’s mountain.

Nearly half the area of both townships is occupied by these mountain-making rocks, which have formerly and in a measure still furnish a large quantity of timber, the bulk of that left being of smaller size and largely marketed for props for the coal mines of the anthracite region. Some timber is still being cut from the flanks of the White and Paddy’s mountains, tributary to the railroad; but the operations are largely in Centre and Mifflin counties.

In the area further north most activity was displayed along the waters of Rapid run, a branch of Buffalo creek, rising in the Brush Valley Narrows, and in the high Medina sandstone flat formed by the junction of Seven Notch and Shreiner’s mountains between which ridges the main stream flows in a narrow and deep valley of lower Clinton rocks.

From the entrance of the narrows in West Buffalo township to the Centre county line beyond the Half-Way Hotel, this valley, for about 8 miles, is exceedingly rough and wholly given up to lumbering. Four steam mills and one water mill were in active operation during the summer of 1888, all of them practically “cleaning up” the large timber tracts, from which most of the large trees had been