Suburban Geology of Richmond, Indiana. 289 



Vegetable matter, - 2.25 



Silica, - 75.84 



Alumina, - 7.30 



Oxide of iron, - 2.23 



Manganese, a trace. 



Carb. of lime, - - - 8.46 



" " magnesia, - 1.27 



Sulphate of lime, - .69 



Phosphate of lime, - - - 1.40 



Potash, - - - - .56 



100.00 

 I suspect much of the carbonate of lime noted in the above 

 table, is due to the infiltration of the calcareous water constantly 

 trickling over the sediment in the channel of the obliterated 

 stream. 



The two ancient channels on the east side of the river, are 

 indicated by the greater quantity of bowlders in them, and in 

 the diluvium directly above them, together with the grooved and 

 smoothly worn state of the rock. They contain no silt ; and the 

 water appears to have run northwardly over the naked rock, into 

 a ravine not far off, for the smoothed edges of the strata at the 

 point exposed denote the former existence of a waterfall of sev- 

 eral feet, with a northern pitch. At the foot of the little cascade 

 was found a granitic bowlder two or three feet in diameter, rest- 

 ing in a cauldron-like cavity, apparently formed by the sand and 

 gravel being twirled around the bowlder by the falling water. 

 The outlines of these smaller beds are fast becoming obscured 

 by the mouldering " marlite," and the vegetation upon its expo- 

 sed surface. 



Fossils. — The profusion of exuvias in our blue limestone, at- 

 tracts the attention of even common observers, who see in their 

 unusual forms, fantastic and fanciful resemblances. But under 

 the eye of science, their honey comb, twigs and frogs, become 

 various forms of coral • their snakes prove to be the univalve 

 shell Orthocera ; their parrots' heads are the bivalve called Atry- 

 pa ; their buffalo horns are converted into Cyathophylla ; their 

 terrapin into a water-worn stone ; and their buttons are trans- 

 formed into encrinites. 



Vol. xlit, No. 2.— Jan.-March, 1843. 37 



