UNION MORAINE. 481 



From the meridian of Peru eastward to the point where the Missis- 

 sinawa moraine comes to Eel River (near South Whitley) there are 

 occasional ridgings of the drift on the south side of this stream and nearly 

 parallel with it, which have perhaps the same age as the ridged belt, though 

 it seems more probable that they are older. The ridges are one-fourth to 

 one-half mile in width and 10 to 30 feet high. They preserve continuity 

 in some cases for 2 miles or more, but are usually a mile or less in length. 



THICKNESS AND STRUCTURE OF DRIFT. 



The thickness of the drift along the line of tlie Union moraine ranges 

 from 20 feet or less up to 300 feet or more. This includes the drift 

 deposited previous to the ice advance which produced this moraine as well 

 as that of the moraine itself The thickness as estimated by the relief of 

 the moraine probably represents approximately the amount of material 

 deposited during this ice advance and shows it to be on an average but 20 

 to 25 feet. A succession of till sheets beneath portions of the moraine near 

 Sidney, Ohio (described below), also seems to indicate that the thickness 

 was increased only a few feet by this ice advance. 



In structure the predominant material is till, there being but few 

 gravelly knolls and but little assorted material interbedded with the sheets 

 of till. This moraine and the later ones of this lobe are locally known as 

 "clay belts," to distinguish them from the plains between moraines, on 

 which there is a black soil; but moraines and plains alike are underlain by 

 till, and, with local exceptions, the till constitutes the soil and subsoil. The 

 till differs from the deeper portions of the drift sheet only in the amount 

 of weathering and the addition of humus. It is more clayey and compact 

 and the soil less warm than in the main morainic system. In a few places 

 sui-face bowlders occur in great number, but as a rule they are no 

 more numerous on the surface than in the deeper portions of the di-ift 

 sheet. In this respect this moraine differs from the main morainic system, 

 on whose surface -bowlders are more numerous than in the deeper portions ; 

 but it resembles the later moraines, none of which have (except in small 

 areas) a markedly greater number of bowlders at the surface than in the 

 body of the drift. It may be remarked in passing that the similarity 

 between the surface and the deeper portions of the diift, the compact 

 character of the till, and the gradual slope on the inner face of the moraine 



MON XLI 31 



