1857.] An Explanation — Geology of Ohio. 255 



inexliaustible fertility, and with the capacity of sustaining a popu- 

 lation more than quadruple the present inhabitants, the distant 

 stockholders will feel assured that the value of investments in this 

 road must be enhanced, from year to year, by the annually increas- 

 ing ratio of travel and of freights which will be secured to it, until 

 the population reaches its maximum density. 



The geology of the territory intersected by this railroad is not 

 complicated. The rocks belong to the secondary class, and to the 

 geological division, or formation, called Silurian. They are natu- 

 rally divided into Upper Silurian and Lower Silurian, corresponding 

 very nearly to the European formations bearing these names. The 

 strata of which the lower division is composed are nearly horizontal 

 at Cincinnati and Hamilton ; but from about the State line between 

 Ohio and Indiana, they have a moderate dip to the west. These 

 strata are composed of alternate beds or layers of limestone and 

 marlite. The marlite is composed mainly of the silicate of alumina 

 and lime, and resembles clays of various shades of grey and blue. 

 The limestone is mostly of a blue color, audits strata, with those of 

 the marlite, range in thickness from an inch or less to one, two and 

 three feet — the marlite, however, mostly predominating. This ar- 

 rangement has been very favorable to the intermingling of the ele- 

 ments of the strata while decomposing, and has given to the soils 

 thus produced an abundance of carbonate of lime, constituting an 

 inorganic basis of great fertility. This Lower Silurian occupies the 

 distance between Cincinnati and a point six miles west of Conners- 

 ville, Indiana, where, on ascending the main ridge west of the White- 

 water river, the Upper Silurian rocks are presented. 



These Upper Silurian rocks are also limestone of a buff gray color 

 mostly, with but a small proportion of marlite between the strata, 

 and are, generally, readily decomposed by atmospheric agencies. — 

 This formation extends nearly to the termination of this road, but 

 is mostly covered by the Diluvium described below. It has been 

 called the Cliff Limestone, by Dr. Locke, on account of the precip- 

 itous cliffs which it forms along the streams of water that have cut 

 their channels into its strata. Wherever the rocks of this forma- 

 tion have supplied the materials of soils, great fertility usually 

 prevails. 



Reposing irregularly upon both classes of the rocks already de- 

 scribed, is an additional formation known as the Drift, or Diluvium. 

 It is composed of boulders and pebbles of various sizes and classes 



