QUATERNARY AGE. — RECENT PERIOD. 561 



country, twenty-five miles wide and fifty long, in western Indiana, is 

 described by F. H. Bradley as one of these obliterated lakes. 



The Great Salt Lake, which is now not over sixty feet deep, lost 

 nine hundred feet in depth at this time, and contracted proportionally 

 in area ; and other large lakes, in the Great Basin and at the eastern 

 foot of the Sierra Nevada, lost equally in their dimensions. The 

 rivers dwindled to one-tenth their former magnitude, and became nar- 

 row threads of water, with contracted flood-grounds between wide ter- 

 raced alluvial plains, whose limits — once their flood limits — afford a 

 ready means to the eye of marking off the contrast. 



In Europe, the elevation of which the terraces are testimony appears to have ended 

 in a second Glacial epoch. Marks of this epoch may yet be deciphered in America. 

 Remains of the Reindeer have been met with in New Jersey and New York; and their 

 occurrence so far south may be in consequence of. such an epoch. The destruction of 

 the Elephant or Mammoth of Champlain America, and of the great Sloth-like beasts 

 and their cotemporaries mentioned beyond, may have been a consequence of it. But 

 the Mastodon and some other Champlain species probably survived into the later part 

 of the Recent period. 



On the coast of Maine, there are large Indian shell heaps of the common Clam ( Venus 

 mercenaria, the Quahog of the Indians) and, in some places, of the Virginia Oyster, spe- 

 cies which are now nearly extinct on that cold-water coast. As made known by Verrill, 

 there is a colony of living southern species in Quahog Bay, near Bath (twenty miles east 

 of Portland), among which are Venus mercenaria Linn., Modiola plicatula Lam., Ilya- 

 nassa obsoleta Stimp, Urosalpynx cinerea Stimp., Crepidula fornicata Lam., Asterias 

 arenicola Stimp., Eupagurus longicarpus Edw., and others, reminding one strongly, as 

 Verrill says, of the coast fauna of New Haven, on Long Island Sound; and the Venus, 

 llyanassa, Modiola, and other species occur also in Northumberland Straits, in the 

 southern part of the Gulf of St. Lawrence. At the mouth of Damariscotta River, thirty 

 miles east of Portland, there is the only locality of the living oyster north of Massa- 

 chusetts Bay. Shells of Oysters, Clams, and Scallops (the southern Pecten irradians 

 Lam.) are abundant in the deeper portions of the mud of the harbor of Portland- 

 These species are relics of a past abundant southern population ; none of the shells are 

 found in. elevated beaches; and hence the migration from south of Cape Cod took place 

 in the Recent period. Such a migration, extending to the St. Lawrence Gulf, was not 

 possible, unless the Labrador current had first been turned aside; and no change would 

 have brought this about, short of a closing of the Straits of Bellisle, by a union of New- 

 foundland to the continent. This implies an elevation of about two hundred feet; and 

 it may be that the one which introduced the Recent period carried the continent, to the 

 north, to this height above the present level. Such an event would have been in har- 

 mony with the occurrence of a second Glacial epoch. 



III. Recent Period in Europe and Great Britain. 



The Reindeer era or Second Glacial epoch, which opens the Recent 

 period, was a marked one in British and European history. Evidence 

 of it is found in the Glacial deposits of the Alps and of the river 

 valleys leading from these mountains ; in similar phenomena, though 

 as yet less well understood, in Great Britain ; in the occurrence in 

 southern France of remains of Arctic and Subarctic quadrupeds, among 

 which the Reindeer was prominent; in the occurrence, as explained 

 beyond, of skeletons and tusks of the Elephant of the Champlain era 

 38 



