Siluro-Cambrian limestone No. II, of the Kishacoquillas and Black Log valleys, a much lower formation, and to accent strongly the position of these important limestone beds, to which the Lewistown valley owes much of its fertility and charming scenery. The group is so well developed here that the formation often carries the name of the “Lewistown Limestone,” and to follow its course through the Juniata is only to pick out the most fertile and the most highly cultivated portion of the region lying contiguous to it.
It may be conveniently divided for description into two sub-divisions, (a) an upper lime-shale division, and (b) a lower massive limestone division. The upper of these two divisions abounds in fossils; the lower furnishes but few. Again the upper is rarely burned for lime unless the lower member is covered up or difficult to reach, while the massive member furnishes nearly everywhere one or more beds of most excellent quality, some of it good pure stone, free from siliceous matter, suitable for furnace use, plastering and all purposes where high grade lime is required.
In Perry county (see Rep. F², p. 60) Prof. Claypole divides this formation as follows:
| 1. White flint shales, | 10′ | Lower Helderberg No. VI 348′ thick. |
| 2. Yellow flint shales, | 80′ | |
| 3. Black cherty limestone, | 8′ | |
| 4. Clark’s Mill lime shale, | 150′ | |
| 5. Lewistown limestone, massive, | 100′ |
Nos. 1, 2, 3, in which Prof. Claypole has found fossils of the Lower Helderberg type, have been included in the Oriskany (Stormville) shale division of No. VII in this report, not upon palaeontological grounds, but because of the general character of the group, which consists of sandy slate and calcareous-siliceous shales, forming really a transition series between the coarse friable sandstone No. VII and the upper lime-shales of No. VI. With a view of representing the economical features of the district as far as possible, these flint-shales have been colored yellow, and included in No. VII, leaving the lower members of the section, Nos. 4 and 5 about 250′ thick, to represent No. VI.
