OGLE COUNT V. H7 



thin layers of the sandstone while in course of being deposited. At a 

 little ravine between Oregon and Mt. Morris they lay in piles, as if an 

 old pot fouudery had once existed there. At the crossing of a smnll 

 stream between Dixon and Daysville. where an old raill-daui had once 

 been bnilt. and a low outcrop of red St. Peter's sandstone may be no- 

 ticed at the right of the crossing, they lay over the hillside and in the 

 road in -Teat abundance. On many of them, ripple marks, as perfect 

 as when made in the soft sand of the old Silurian beach, still exist. 

 They are the eddies and ripples of the Silurian seas turned to fossils, 

 and preserved in the embrace of iron and sand. 



Again, these sandstone hills resist atmospheric agencies in a wonder- 

 ful de-Tee, eonsideriug the soft and friable nature of their composition. 

 Oftentimes where they are most abrupt one can pick holes in their per- 

 pendicular sides with his knife, or strike his pick into the solid-looking 

 mass. One would expect that such masses would crumble to pieces and 

 sink into low. white sandbanks, but such is not the case. They pre- 

 serve their forms as well as the limestones, and have quite as little 

 debris and talus piled about their bases. 



The color of this sandstone is of all shades, from the whiteness of 

 crushed sugar to chrome yellow, and the many tints of brown and red. 

 The color is a stain produced by the oxyd of iron held in solution in 

 the waters, which have at various times percolated through the sand- 

 stone mass. Where this dye was absent in the percolating water a 

 sandstone as white as granulated snow was the result: as the dye was 

 present in the water, in that proportion are the sandstones colored and 

 stained. 



In consistence this sandstone is saccharoidal, or sugary, and much of 

 it is held together by the slightest cohesive attraction. In many places, 

 especially where the sandstone was very white, I found difficulty in ob- 

 taining cabinet specimens. Every blow of the hammer would shiver 

 the block to pieces. But this is not always true. I saw houses built 

 from this material which seemed to be hardening into a fair building 

 stone: and Dr. EVERETT gives an account of an arched railroad bridge 

 built over Franklin creek, in Lee county, from the same sandstone. In 

 a few places it seems to have become hard and crystaliue; in a few more 

 it has cohesion enough to make an indifferent building stone; but its 

 general character is soft, friable, and uncohesive. 



Under a strong microscope the grains of the white variety appear 

 limpid and semi-translucent : those of the darker varieties appear as if 

 coated over by rust. All the grains are round, similarly formed, and 

 similar in si/e. The grains are quite small, and the mass is remarkably 

 ptue and homogeneous in character. These incoherent, crystaline 

 grains of transparent quartz owe their darker colors, where colored, to 



