POSTGLACIAL OXIDATION 201 



''Slate. — The outcrops of slate south of the moraine of Ijowis ami Wright 

 are under a cover of gravels. Near Slatington workable slate is (luarried 

 iunuediately under these gravels, and there is no difference in appearance 

 between them and the gravels of the terminal moraine. 



''Coal. — The gravels at Morea, Pennsylvania, are neither oxidized nor rotten, 

 nor in any manner capable of separation from the gravels of the Lehigh water 

 level or of the moraine. They are abundant in sands, which are like the sands 

 of the Pocono outcrops, or at Glen Sununit. I'ennsylvania. or above the coal 

 outcrops north of the moraine of Lewis and Wright, and there is nothing to 

 distinguish them either in color, degree of disintegration, or other character- 

 istic dependent on age from outcrops to the north. They are 10 feet thick on 

 an average. Immediately under them are the vertical outcrops of the mam- 

 moth bed. Weston Dodson and Company mined this bed and sent every par- 

 ticle of the same to market. Analysis of fixed carbon and {\sh in samples 

 taken immediately under the gravel and 100 feet underground showed that 

 there was not 2 per cent of difference between the samples and between 

 samples of the same bed. which were flat and not in any manner influenced 

 by surface water. Now, it is a well known fact that samples from the same 

 bed and the same belt in the bed taken 10 feet apart may differ from 5 to 10 

 per cent in these things, and I have seen in the same mine a bed 11 feet thick 

 of clean coal gradually diminish to a dirt bed 1 foot thick, and that within 

 1.000 feet. We can. therefore, conclude that the 2 per cent variation shows an 

 agreement between the two samples at the surface and inmiediately under the 

 gravel, and at depths as great as between any two samples of coal in any 

 anthracite mine. 



"On the other hand. 1 mile south of the limit of the 'border' and the mine 

 next to it there is the usual 'peacock' coal in the outcrop, showing influence 

 of weathering and the inclosing rock rotted soft for several feet from the 

 surface, as is the usual occurrence, and this also occurs north of the i)order,' 

 where the ice poured over a ridge and left the outcrops immediately below the 

 crest untouched, as in the 'crag and tail' cases, which are infinite in number 

 and identical. 



''Loss of caleite in glacial deposits. — The Hydesville, Pennsylvania, overwash 

 gravels of the moraine of Lewis and Wright are taken as of the latest age. 

 These are cemented by caleite, and the shells in the red sandstone are gener- 

 ally dissolve'd to form the binding material, as is also the case in the gravels 

 near Warren at both high and low levels, so that there is no difference in the 

 induration from caleite cementation to be seen between the 'hard-pans,' as 

 they are called, before and behind the moraine. The marine shells in the 

 drumlins of Massachusetts have disappeared and their place is taken by sand 

 concretions cemented by their caleite. These are behind the moraine of Lewis 

 and Wright and so of the latest period. In fine there is evidence that gener- 

 ally the caleite in the glacial deposits, in the form of shells, has been leached 

 away either before or since the deposit of the fragments in the drift. This is 

 not always the case, and about Wai i(mi. Pennsylvania, cobbles have been found 

 with portion of the shells undissolved in gravels, which can be traced con- 

 tinuously from the alleged 'rock-shelves' to the present levels. 



"Now, from these evidences it seems that the times of the 'border' were very 



