SALT BASINS OF WATERLIME AND ONONDAGA 339 



logical period than those elevations of far wider extent which introduced 

 the Oriskany faunas. These latter elevations brought about conditions 

 in the extreme east of America quite similar to those of the Old Red 

 sandstone of the opposite side of the Atlantic. The rarity of merostomes 

 and fishes in the Gaspe sandstone does not disprove its general equiva- 

 lency in time with the Old Red Sandstone period of Wales and Scotland. 



If we approach the subject from this wider point of view and follow 

 it down into the particulars of equivalency, the details confirm the 

 grander facts. In the Maine and New Brunswick region, though there 

 is evidence of continuous sedimentation from the base of the Silurian 

 (Anticosti series) through to the Carboniferous, there is no evidence of 

 the local shutting out of the sea, represented by the Guelph, Onondaga, 

 and Waterlime of the interior continental region farther inland. 



Nevertheless, the Silurian faunas of these eastern provinces pass 

 through the same faunal evolution observed in the Niagara, Lower Hel- 

 derberg, and Oriskany stages of the interior, but the separation of the 

 faunas is less marked. In the Anticosti and Gaspe limestone faunas the 

 passage from Niagara to Lower Helderberg is gradual. In several re- 

 ported cases in this eastern province, species (such as Ralysites catenularia) 

 which in the interior are characteristic of Niagara and lower range up 

 into association-with a fauna which in its general facies is equivalent to 

 the Lower Helderberg, and in the Gaspe limestones the passage upward 

 is still gradual until traces of the Oriskany appear, thus indicating a 

 continuation of similar environmental conditions throughout the whole 

 of Silurian time without the marked change of conditions represented 

 by the Onondaga formation of the interior. 



On the other hand, there was a marked change of conditions for the 

 whole eastern province at about the time of the Oriskauy fauna. In 

 the Gaspe peninsula this is represented by the change from limestone to 

 sandstone, and an almost total disappearance of marine species, and the 

 frequent presence of land plants. 



In eastern Nova Scotia, at Arisaig, the same transition is seen, while 

 in western Maine the marine fauna does not cease till after the Oriskany 

 fauna has appeared. This great change in conditions, contemporaneous 

 with the appearance of the Oriskany, is evident in New York and down 

 the Appalachians as far as Virginia, Tennessee, and even on to Georgia 

 and Alabama. 



INTRODUCTION OF ORISKANY FAUNA COINCIDENT WITH ELEVATION OF 

 PRESENT ATLANTIC BORDER OF CONTINENT 



Thus the evidence is quite clear to one studying the minute details 

 of the case that it was the introduction of the Oriskany fauna which 



