292 E. H. WILLIAMS, JK. EXTRAMORAINIC DRIFT. 



never entirely disappear, and are found continuously to South moun- 

 tain. Such a section has been traced from Germansville through Pleas- 

 ant Corner, Lowhill, Fogiesville, Trexlertown and Alburtis. . The crushed 

 and bent slates are carried almost across that formation, and slaty till in 

 a perfectly rotten state is found on fresh limestone just north of Fogies- 

 ville. The large bowlders are carried over several steep ridges, but could 

 not surmount that south of Switzer creek, so that the rest of the region 

 is free from very large stones. The county bridge over the Jordan near 

 Pleasant Corner is built of large cut stones from the bowlders brought 

 over the Blue ridge, and the latter are as fresh as if recently taken from 

 the quarr}^ Those with a calcareous matrix must be of recent forma- 

 tion, as an extended exposure reduces them to sand. 



Over the limestone belt the till is a bowlder-clay of a reddish brown 

 to reddish yellow color, carrying a few pieces of the country rock ; 

 but the burden is mainly fragments of chert, rolled quartz from the 

 slate, and foreigners from and beyond the Blue ridge. East of the 

 Lehigh we find the gravels and bowlders scattered over Northampton 

 county, and a number of lines of stones across the Saucon valley mark 

 the short stoppages of the ice on its retreat; but west of the Lehigh 

 there is but little gravel and few bowlders over the limestone and the 

 lower part of the slate, but slaty till is found on slate, and limestone frag- 

 ments and clay on limestone. The" moraine lines in the Saucon show 

 that the ice moved southwest originally, but the change in the trend of 

 of South mountain exerted a pressure on the glacier and altered its 

 direction to one parallel to the axis of the valley, as shown by the dis- 

 tribution of the till just noticed as well as by the shape of the lowest and 

 most southern range of slate hills, whose longer axes and slightest slopes 

 are parallel to the direction just mentioned. The ice-movement was, 

 therefore, southwest until the pressure of the ice heaped against the 

 northern flank of South mountain resulted in a more westward motion. 

 The melting of this accumulation formed the great lateral moraine that 

 we find between Seidersville and Temple. It is shown in the railroad 

 cuts at Emaus, Topton and Temple and consists mainl}^ of pebbles of 

 sandstone, with a small amount of trap and gneiss. These are seldom 

 larger than the hand and the finer part of the till is more sandy than clayey. 

 At Topton the cut is 17 feet deep, and just beside it is a well sunk in 

 gravel for 80 feet before striking limestone and water. This would make 

 the thickness nearly 100 feet. At Temple the cut is 20 feet deep and a 

 well near by is 97 feet deep, but no record of the material passed through 

 or the depth of the limestone could be obtained. The well-top is much 

 below the track, so that the bottom would be about 150 feet below the 

 level of the top of the gravel. This will be again referred to. 



