Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/234

206 F³. north, and the Georgetown anticlinal axis on the south below MecKee’s Half Falls, which elvateselevates [sic] a small area of the Oriskany and Lower Helderberg rocks near the junction of Mahantango creek and the river.

Between these two main flexures, however, there are several subordinate anticlinal and synclinal rolls, none of which can be traced west into Juniata county; but which have sufficient strength along the Susqnehanna river to duplicate and spread the outcrops of the Devonian measures through a belt of country 4 miles in width.

The Catskill rocks No. IX occupy a triangular-shaped area about 2 miles in width along the river, and narrowing to a point 3 miles further west. They are largely red shales and sandstones and are best exposed in the bluffs along the river. South of the aqueduct which carries the canal over on to the Isle of Que, there is a splendid exposure of these red rocks for 400 yards along the road on dips varying between 35° and 45° S. 15° E., with a slightly steeper 50° dip at the aqueduct and school-house, and a similar one at the south end of the exposure, where the higher beds have a greenish-gray cast. Elsewhere they are uniformly red and consist of about one-half sandstone and one-half shale, very regularly bedded and some of them furnishing excellent building-stone.

After an interval of 10 or 15 yards south of this exposure the dip flattens for a short distance to 25°, but soon in- creases again in red and gray sandstone and shale to 40° and 45°.

The upper or central portion of the formation occupying the trough of the basin, is Jess massive ; but the top layers have been somewhat quarried a short distance south of the public road leading west and up the ridge, where they show massive greenish-gray and red sandstone suitable for building purposes. The entire thickness of the Catskill rocks exposed on either side of the Shamokin synclinal in this township cannot be less than 3500′ and may reach 4000 on careful measurement.

The exact position of the synclinal cannot be positively