110 NEW YOIIK STATE MrSElM 



in a number of localiiies in the Appalachian n*gion^ The occur- 

 rence of conjrlomerate beds resting on the limestones from which 

 they were derived, suggested to that experienced observer that 

 the sea bed was raised in ridges or domes above the sealevel, and 

 thus subjected to the action of seashore ice» if present, and the 

 aerial agents of erosion. While no dinn't connection has been 

 noteil bi'tween the lower Tivnton c<jngloinei*ate and the youngest 

 limt^tone bed represented in it, the assumption of the presence of 

 suih ridges or domes in tin* ApjKilachlan region is in accord 

 with our knowledge of the i-onstant movements going <m in thi» 

 region throughout the Paleozoic era, and coincides with the 

 iU^um]»tion of ba'rriei-s in this i-egion made by other writers. It 

 is theivfoi*e quite i»o<«sible that the as?«umed transgression*? 

 opened the crest of one of these ridges or domes, and thus laid 

 bare at once to the abrading action of the waves, a series of beds 

 extending from the Cambric to the last deposited Ti*enton lime- 

 stone, and furnished the various materials for the conglomerate 

 and the oalcai*eo-ai-enaceous mud of the matrix. These were 

 dejK^sited on the Normans kill shales forming in the deeper water. 

 While the presence of temporary coast lines, or the exposures 

 of the various beds represented by the pebbles, to wave action, 

 caused by the rising of broad ridges to the surface of the lower 

 Trenton sea, may be infeiTed with some degree of certainty, the 

 great variation in the size of the boulders and [>ebbles presents 

 some difficulty to these attempts at explanation. Some of the 

 boulders attain a diameter of several feet. The action of coast 

 ice, api>ealed to by Dawson for the c^xplanation of the lower 

 Siluric c<mglomei*ates near the St Lawi'ence river and suggested 

 by Walcott as an alternative theory for the origin of some of the 

 Cambric conglomerates, may in the writer's judgment be 

 excluded here on account of the [iresence of the Trenton fossils, 

 including corals, in the matrix. But it is highly probable that 

 the action of strong tidal or coastal currents, caused by the ob- 

 lique impact of the waves on the coast, was engaged in spreading 

 I he material derived from the coastal or abraded region over a 



* OeoL j*oc Am. Bui. 18»S. 5:191. 



