Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/50

From Wikisource
Jump to navigation Jump to search
This page has been proofread, but needs to be validated.
22 F³.
E. V. d’Invilliers, 1889.

12. The Cowan synclinal is the next trough south, first making its appearance at Cowan in Buffalo township, and easily traced westward as a narrow fold of Salina and Clinton rocks, closely hugging the south base of the Little Buffalo mountain, and crossing the Lewisburg and Bellefonte turnpike near the old hotel on Laurel run.

13. Paddy’s mountain anticlinal, a double flat roll of Bloomsburg red shale where first seen south of Cowan, but showing only a single fold of Clinton rocks at Pleasant Grove church in Lewis township; crossing the Bellefonte turnpike at the forks of the road to Laurelton with dips of 10° and 20° in the Iron sandstone, and soon elevating the Medina sandstone in the Paddy mountain spur in Hartley.

Thus far it has been seen that each succeeding trough south of White Deer mountain has deepened slightly along the river, to contain geologically higher and more recent rocks. The Mifflinburg synclinal however, to be soon described, is an exception to this rule, for it is geologically deepest near the center and contains in its trough a synclinal ridge of Lower Helderberg limestone 7 miles long, south of Mifflinburg, capped in places with Oriskany standstone.

14. The Hartleton sub-division of the Buffalo Valley synclinal, the first basin south of Paddy’s mountain, is largely local in this county. It is overshadowed by the deeper basin at Mifflinburg further east, but it can be traced west of Hartleton for 8 miles as a narrow valley of upper Salina lime shale land, flanked on either side with bands of Bloomsburg red shale with converging dips of 30°-35°, and by the shoaling up of the succeeding Clinton valley along Penn’s creek further west, begins to assume new prominence in Mifflin and Centre counties as the Long mountain synclinal.

15. The Vicksburg anticlinal is of almost equal insignificance, although it can be more or less distinctly traced from the river about 1½ miles below Lewisburg. This is the expiring end of the great Montour axis of Montour and Columbia counties.

Its crest is there composed of the top layers of the Clinton formation, and as the axis sinks towards the west it