GEOLOGICAL KEPOKT. 



harder and softer, or coarser and liner, portions of the strata vary con 

 relative thickness. What appear to be rocky strata are frequently n< 

 but merely concretionary seams. Wherever large masses of the hlu 



nniform, without a distinct stratification. After some time, howevei 

 tions wear out under the atmospheric influences, while the harder on 

 more or less horizontal lines, are left protruding, and thus indicate 

 but as the harder and softer portions are not regularly distributed 

 false stratification is deceptive, and apt to lead to great errors in the 

 thickness and extent of the strata. 



In these rocks, near the forks of Platte River, 1 found numerou 

 of the size of a small cherry-stone, apparently related to the living g< 

 have improperly been called Lithospi'niHiM, which name belongs to a 

 ing genus of plants. The same were noticed, together with a Helix, i 

 the mouth of Ash Hollow. On the northern bank of the South Piatt 

 the crossing, a silicified fragment of a large bone was obtained ; but 

 decide whether it originated from these strata or had been washed c 

 a lower geological horizon, higher up the river (see below). At 8 

 strata contain numerous concretions of sand, of a peculiar shape, pai 

 much like bones of large animals, that many people have been decei 



