Singular conformation of Limestone. 19 



Gomposed of a kind of quartzose sand, of a gray or reddish 

 gray colour, and is possibly a variety of the mill-stone grit 

 of the canal district. Shell lime rock occurs in great 

 abundance in the vicinity of the Oolitic series, but its rela- 

 tive position, in reference to this formation, I am not at 

 present able to determine. 



Since writing the above communication, I have been 

 highly gratified by an interview with Mr. Schoolcraft, who 

 informs me that Oolite actually occurs in Munroe township, 

 Gallatin county, Illinois, near the Ohio, four miles west of 

 Cave in the Rock, in detached masses, and, descending 

 into some of the old diggings, made for the purpose of 

 procuring lead, he found it in situ, regularly stratified. Mr. 

 Schoolcraft thinks, from all the observations which he was 

 able to make, that this Oolite rests on calcareous sand rock 

 and is overlaid by shell limestone. 

 ■ Saratoga Springs, J^ov. 25th, 1824. 



Art. IV. — Notice of a Singular conformation of Lime- 

 stone, by Prof. Dewey. 



In blasting the rocks near the College, a singular con- 

 formation of limestone has been exposed to view. It be- 

 longs to the bed of limestone, which contains a consider- 

 able proportion of siliceous earth, and whose seams are 

 lined with talc, and appears to have been covered by the 

 strata of limestone lying parallel to those still remaining. 

 The figure accompanying this paper, is a perpendicular 

 section of the rock. The general inclination of the stra- 

 ta, shown by the line A B, (see plate 11.) is about 40° and 

 the dip is towards the east. The section shown on the 

 plate, is nearly at right angles to the direction of the strata, 

 so that E W lies nearly east and west. The strata, which 

 lie upon A B, are divided by natural seams into large 

 blocks, which are above, and below, and eastward of B. 

 Commencing on these are several strata from one to eight 

 inches thick, which are curved in the manner represented 

 between B and W. The outer strata have a larger curva- 

 ture ; but the inner finally come to a point, as at C and D, 

 the two parts forming the angle being clearly defined but 

 closely compacted into a solid mass. At E is another 



