main Juniata trough, and crossing the Susquehanna river at the junction of the North and West branches at Northumberland. in Catskill red sandstone No, IX, with converging dips of 10°-15°.
The line of this great trough is distinctly marked through Snyder county, and is generally occupied by high land. It carries the Catskill measures for 15 miles in its basin, which shoals and contracts westward from the river, as is indicated by the map coloring. From a point northwest of Middleburg to the Juniata county line, its rocks are everywhere Devonian, with only the lower members of No. VIII, or the Marcellus and Hamilton slates in the western townships.
The axis is well seen on Penns creek near Kratzerville, with dips in Catskill rocks of 10°-15°; passing thence westward a little north of the Lutheran church in Jackson township to the M. E. church and school in Centre town ship; then north of Zion church to Adams township, with dips in Chemung rocks of 25° and 30°, where it curves slightly southwest with the valley, keeping a little north of the Centre line and the Lutheran and Methodist churches in West Beaver, until it finally passes out of the county south of Bannerville. It is everywhere an exceedingly regular and normal synclinal, apparently without any subordinate rolls, and gradually deepens toward the river.
There are one or two small anticlinal rolls in the limestone and lime shales of the valley between Beavertown and Paxtonville, and one economically important dimple in the Clinton measures south of Adamsburg, which will be mentioned in detail later.
3. The Shade mountain anticlinal is the next prominent structural feature, running through the great mountain range of that name to Juniata county, and crossing the river above Selinsgrove into Northnmberland county, where it has subsided to such an extent as to barely carry on its crest the Lower Helderberg No. VI and Oriskany No. VII for about 2 miles from the river, beyond which point the Marcellus and Hamilton rocks come in and extend to the Columbia county line.
