Between the western extremity of the Appalachian coal-field and Cincinnati, as will be seen by referring to the section given at p. 92. Vol. I., the different formations, from the Devonian to the Lower Silurian inclusive, come up to the surface in succession, being well exposed in the cliffs or steep slopes of the hills which bound the Ohio valley. I have already mentioned a fine seam of coal at Pomeroy, beneath which, farther to the westward, the lower coalmeasures are seen, and at length at Portsmouth, the inferior conglomerate or millstone grit, next to which, the formation, called by the Ohio geologists the Waverley sandstone, the equivalent of the Devonian formation (No. 9. in the large map, PI. II.), makes its appearance. To this sandstone, the Upper Silurian slates and limestones (Nos. 10, 11. and 13. of the map) succeed in the descending order, and lastly, at Cincinnati, the Lower Silurian groups (Nos. 14. and 15. of the map) are exhibited in the hills, and in the bed of the Ohio at low water.

Having, when I came down the Ohio, made the last part of my journey in the dark, I re-ascended the river for a hundred miles, in company with Dr. Locke, a geologist lately engaged in the State survey of Ohio, and who liberally devoted his time to aid me in my inquiries. I was desirous of seeing the rocks corresponding to the Old Red sandstone before mentioned, and with this view we landed at Rockville, about eighteen miles below Portsmouth, and examined the Waverley sandstone at that place.