BUFFALO SOCIETY OF NATURAL SCIENCES 115 



which I offer the following suggestion. The only decomposition pro- 

 duct in which alumina is higher than silica is laterite which might 

 have been formed either during the Salina, to the north of the desert 

 in which the limestones were disintegrating, or else during the Mon- 

 roan when the arkoses previously formed by mechanical breaking up 

 were subjected to decomposition. That the northeastern portion of 

 Atlantica was of a more pluvial character than the northern part 

 which supplied the lime mud is independently inferred from the 

 character of the deposits formed in western Europe at this time. 

 For here the semi-arid conditions existed on the eastern side of the 

 highland which supplied the sediment, indicating that the moist region 

 lay to the west, where the great southward flowing rivers of Atlantica 

 appear to have had their source. 



So far it has been shown that the Bertie waterlime is of clastic ori- 

 gin, and that the sediments were river-transported from the north. 

 The fine stratification of the deposit and layers of sun-cracks in cer- 

 tain localities are structural features indicating that the muds were 

 deposited in quiet waters, while the nature of the fauna has shown 

 that the place of deposition could not have been in the sea, either far 

 from shore, or in any protected, littoral portion; the only remaining 

 place is on the land. In concluding this discussion, therefore, we may 

 test the hypothesis of the flood-plain or delta origin of the Bertie by 

 determining whether it accounts for all the facts. We are to imagine, 

 then, two rivers flowing from the low- lying Canadian area southward 

 until they empty into the slowly-advancing Upper Siluric sea. Ma- 

 rine deposition would be active to the south and if the rocks now cov- 

 ering the Monroan in southern New York and northern Pennsyl- 

 vania were removed, we would expect to find the mixed marine and 

 freshwater beds which marked the interfingering of the delta deposit 

 with those that were laid down in the sea. Unfortunately, at pres- 

 ent we know only the marine Monroan limestones from Pennsylvania, 

 the position of that ancient strand-line being nowhere exposed. If 

 we bear in mind the fact that the outcrop of the Bertie waterlime in 

 New York forms only a narrow belt extending east and west, it is 

 readily understood that the cross-sections of the two eurypterid-bear- 

 ing "pools" are to be interpreted as cross-sections of the two north- 

 south river channels (see figs. 3 and 4). The northward extension of 

 those river courses has been removed by subsequent erosion, the 

 southward continuation to the strand line is covered by later strata. 

 If the Bertie waterlime of the two "pools" represents muds really de- 



