86 The Upper Cretaceous Deposits of Maryland 



sands of the Lower Cretaceous formations. The presence of such exten- 

 sive deposits of arenaceous sediments indicate in all probability a renewed 

 depression of the coastal border and the transportation again of coarser 

 materials into the area of deposition. Many of these materials were 

 doubtless obtained from the earlier Cretaceous strata, but only the more 

 solid quartz grains resisted the processes of transportation. Much, how- 

 ever, was doubtless brought from the Piedmont and Appalachian areas by 

 the streams which had their sources within those regions. 



There is no evidence, however, that marine waters entered the region 

 of Raritan sedimentation since no marine fossils have been observed. The 

 irregular and frequent cross-bedding of the strata suggest that the 

 deposition was partially continental in character combined with sedimen- 

 tation in broad lagoons into which the streams poured a large amount of 

 clastic material. The rapid changes from coarse to fine sand and often- 

 times to clays indicates constantly changing currents with the formation 

 of bars and spits on the floors of the lagoons. The discovery in New 

 Jersey of a few molluscan forms of probably estuarine habitat indicates 

 that the sea could not have been far distant. 



Some of the less sorted materials suggest fluviatile conditions over por- 

 tions of the area particularly at the opening of the epoch, while eolian 

 transportation may well have been a factor as we see so frequently to-day in 

 the proximity of coast lines where sandy deposition is taking place. 



That an extensive flora covered the coastal border and doubtless spread 

 over the upland areas is clearly evident by the abundance of plant remains 

 which are found at certain points where the sediments were of a type to 

 preserve them. Unfortunately no traces of terrestrial animal life have 

 been detected, although such must have existed in profusion during 

 Raritan time. 



The close of Raritan sedimentation was evidently marked by conti- 

 nental oscillations by which the sea floor of that period was elevated and 

 eroded with a subsequent depression that carried the margin lower to the 

 southward than to the northward, with the result that a gradual trans- 

 gression of Magothy deposits takes place from that direction. 



