DRIFT DEPOSITS OF ILLINOIS. 5 



Xo. 1 was found on Skunk river, near its mouth; No. 2, in 

 the river sand at Warsaw, 111.; Xo. 3 is embedded in a nodule 

 of hard ferruginous sandstone, and was found at the mouth of 

 the DesMoines river: Xo. 8 was obtained near St. Francisville, 

 Mo., from drift clays above the flood plain of the river. 



Nos. 4. ."> and 6 were found in the blue clays of the drift at 

 Golden Bluff Vineyards, about two miles south of Warsaw, and 

 their Cretaceous aspect will, no doubt, be readily conceded. No. 

 4 is a Belemnitv, Xo. 5, a fragment of an Ammonite, and No. 

 6 is a tooth of Ptychodus polygyrus, of Agassiz, an undoubted 

 Cretaceous form. 



Xo. 7, is a characteristic Cretaceous Echinoid belonging to the 

 genus Ananchytes, and was found near Petersburg, in Menard 

 county. 



In addition to the Cretaceous fossils above mentioned, I have 

 seen in the collection of the Hon. Wm. McAdams, of Alton, a 

 very large shark's tooth measuring nearly three inches in length, 

 that was found in sinking a well in the valley of the Illinois 

 river, a few miles above the mouth of that stream, at a depth 

 of more than twenty feet below the surface; and also the ver- 

 tebra of a shark found in sinking a cistern on a sand ridge in 

 the same county, at a depth of fifteen feet, taken out in Mr. 

 McAdams' presence. This bone has the dark brown color char- 

 acteristic of the Ichthyic fossils usually found in Cretaceous and 

 Tertiary strata. 



In further proof of the supposition that pre-existing Creta- 

 ceous strata were broken up and partially redeposited at local 

 points in the Mississippi valley during the drift period, we may 

 cite the frequent occurrence of beds of paint and potter's clays 

 at the base of the drift deposits. These clays are generally 

 composed of a fine silicious sediment of various colors, that are 

 KthologicaJly quite unlike the sediments that would result from 

 the erosion of any of the paleozoic rocks occurring in the adja- 

 cent region. 



Hence it seems highly probable, as has been suggested by Dr. 

 White, in the Second Geological Survey of Iowa, that the Cre- 

 taceous deposits once covered a much wider area in the Missis- 

 sippi valley than they now occupy. 



