560 J. K. Hyde — Notes on the Absence of a Soil Bed. 



impression of a calamite stein. In this case, there was no ten- 

 dency to break at the contact. At those localities where car- 

 bonaceous shales or coals with their accompanying white clays 

 rest on the Logan, the basal beds are clearly of the Coal- 

 measures series and not a soil bed antedating the Pennsyl- 

 vanian. 



It is not the purpose to here explain why there is no soil bed 

 present. That seems to involve to a high degree the manner 

 in which the basal Pennsylvanian beds were formed, that is, 

 whether they were truly continental or whether there was 

 subsidence below a body of water and removal of the soil from 

 the Logan hills by wave action. In support of the latter is the 

 occasional occurrence in the basal beds of the Pennsylvanian 

 sandstones of considerable numbers of fossiliferous limestone 

 or chert pebbles which appear to have been derived from the 

 breaking up of some part of the Maxville limestone, which is 

 otherwise unrepresented in the immediate vicinity. However, 

 the presence of the limestone pebbles and the absence of the 

 soil beds are the only features which suggest that the basal 

 Coal-measures are not truly continental or that the interval 

 marked by the erosion plane has been one of greater com- 

 plexity than simple subaerial erosion. 



Whatever may have been the intermediate stages, the 

 occurrence is believed to show that a soil bed or evidence of 

 weathering at an erosional contact is not essential to its inter- 

 pretation as a plane of subaerial erosion, even when the next 

 succeeding beds appear to be of continental origin, and that 

 the absence of such a bed at such a contact may demand a 

 much more complicated explanation than that of simple sub- 

 marine or subaerial erosion. 



