carries down first the Bloomsburg or lower Salina red shale, and then a portion of the upper Salina shale. Its axial line curves north to Vicksburg and then south towards Buffalo creek, where it again begins to increase gradually in strength, until east of Laurelton it brings up the Bloomsburg shale, and the Clinton west of Laurelton. Here it again declines and dies away against the north flank of the White mountain.
16. The Mifflinburg synclinal is shaped like a canoe, its deepest central point being south of Mifflinburg and rising in both directions; eastward to the Susquehanna about a mile north of Turtleville and extending westward, north of Milmont and south of Laurelton, to shoal up along the Lewisburg and Tyrone railroad.
17. The White mountain anticlinal, next south, is of only slight importance in Union county, extending for about 4 miles east of the Mifflin county line, but subsiding so rapidly eastward that the red and white Medina No. IV, the lower Clinton and Ore sandstone are all carried under water level on the railroad east of Weikert station.
18. The Jack’s mountain anticlinal is by far the grandest and most important axis in the county, extending from the river at Turtleville west through Shamokin mountain; crossing Sweitzer run about half a mile below Battletown, where the sand rock has sunk beneath the Clinton shales for about two miles; thence extending along the Union-Snyder line to Mifflin county, where the walls of the mountain have been pushed far enough apart to admit of the east end of the Spiegelmeyer slate valley No. III.
For 3½ miles west of Turtleville the axis carries on its crest only the Clinton rocks; the two opposing outcrops of the Ore sandstone are scarcely one-fourth of a mile apart on the river. The crest of the anticlinal however, is here sunken, causing two anticlinal rolls of the Ore sandstone which come together about a mile from the river, and form a basin shoaling westward, from which a large quantity of ore has been mined.
Where the axis has become strong enough to elevate the Medina sandstone of Shamokin mountain, the same strata,
