66 STEVENSON— FORMATION OF COAL BEDS. [April 18, 



the distinction that in the latter there are the forms known to be 

 characteristic of deep sea zones only. But no such problem as that 

 imagined by Agassiz presents itself in the Coal Measures — though 

 there are those who believe the contrary. Respecting the marine 

 forms of the Coal Measures time one may assert positively nothing 

 beyond the fact that they are closely related to marine types. 

 There is no evidence to prove that they preferred deep water but 

 there is abundant evidence to show that they had no objection to 

 dwelling in shallow depths ; it is sufficiently clear that limestones 

 carrying the typical forms were deposited at many localities where 

 every feature indicates shallow water and close proximity to a shore. 

 This matter has been considered in an earlier part of this work, but 

 it may be well to present additional notes here. 



D. White^® during the summer of 1912 found evidence of pre- 

 sumably shallow water deposition of some Coal Measures limestones 

 in Oklahoma ; Udden has described a brecciated marine limestone 

 near Peoria, Illionis. Ashley^'' found near Merom in Indiana 2 to 8 

 feet of conglomerate, consisting of shale, sandstone and coal pebbles, 

 bedded in calcareous matter and resting on 2 to 4 feet of marine 

 limestone. This conglomerate underlies the great Merom sandstone. 

 A stream flowing over the outcrops entered the sea and dropped its 

 load of coarse material into the unconsolidated upper portion of a 

 limestone containing Productits and other marine types. As the 

 conglomerate is coarse, it must have been dropped at once when the 

 stream entered a body of water. The Ames limestone is impure, 

 conglomerate but fossiliferous at a locality in Meigs county of Ohio, 

 as recorded by Condit ; on the extreme western border in Muskingum 

 county of the same state the Ames is shaly and coarse grained, 

 showing none of the characteristics observed farther east, but it is 

 fossiliferous; in Carroll, on the northwest border, that limestone 

 on the extreme outcrop is very impure, coarse grained and very like 

 sandstone ; at a short distance farther east it is more like limestone 

 but at a mile farther it is earthy and disintegrates on exposure. At 

 these localities, one is very near the original shore, where the water 



''' Letter of October 25, 1912. 



^' G. H. Ashley, " Coal Deposits of Indiana." p. 908. 



