112 THE HABITAT OF THE EURYPTERIDA 



the littoral belt or the deeper sea; such a fauna finds its counterpart 

 in no waters of normal marine salinity, nor yet in those of modified 

 marine salinity, either estuaries, epi-continental seas, lagoons, or other 

 brackish to fresh water dependencies of the ocean. Thus, though 

 we cannot determine with certainty the place of deposition of the 

 muds from the chemical composition, or from other lithological char- 

 acteristics, the fauna indicates with absolute certainty that those 

 muds were not deposited in any portion of the sea. 



From the foregoing discussion it appears that the Bertie water- 

 lime is best interpreted as a deposit of clastic origin, and that the 

 material was transported by rivers. It also appears that this mate- 

 rial could not have been deposited in any part of the sea, for it has 

 not the characters of non-terrigenous deep sea muds, nor the faunal 

 content of a near shore, bay or estuarine deposit. There remains but 

 one place for the deposition of these terrigenous muds and that is upon 

 the land. There seems to be no escape from the conclusion that these 

 lime muds of the Bertie represent the flood-plain or delta deposits 

 from one or more rivers, or else that they accumulated as playa lake 

 deposits. The characteristics of the sediments and faunas of such 

 deposits have been fully described on pages 79-83, and it must be con- 

 ceded that of all the known modes of deposition the lower flood- 

 plain and upper delta regions of rivers come nearest in their physical 

 and faunal characters to those found in the Bertie waterlime, though, 

 of course, the nature of the sediment demands a source of supply in 

 which calcareous material plays a dominant role. 



It should be noted in this connection, that shallow water conditions 

 of deposition for the waterlimes of New York and the associated 

 calcilutytes (Manlius, etc.) are indicated by the occurrence of sun- 

 cracked layers at several points. While these have not been found 

 in the Bertie of the Buffalo region, they are wonderfully developed 

 in the waterlimes of the Rosendale-Rondout regions, and in the 

 Manlius of central New York and elsewhere. 



Considering the waterlime as a flood-plain deposit, the history 

 during Bertie time would be something like the following: 



The early Siluric history of the eastern part of the North American 

 continent had been admirably staged to lead up to the climax of 

 waterlime deposition in many regions during the later Upper Siluric. 

 During the Niagaran there had been a widespread advance of the 

 sea which undoubtedly covered most of southeast and central Canada , 

 as we may judge from the remnants still to be observed in the Lake 



