410 Sir H. Hoivorth — Recent Changes of Level. 



valley is now submerged to a depth of over 3000 feet, and is the 

 representative of the channel of the ancient Mississippi River, towards 

 which it heads." 



On the Pacific coast, in the region of Cape Mendocino, Professor 

 George Davidson has identified three valleys, now submerged, from 

 2400 to 3120 feet, and several of inferior depth. These measure- 

 ments are those of the valleys where they break through the 

 marginal plateaux of the continent at about six miles from the 

 present shore, where it is submerged to the depth of a hundred 

 fathoms. Similar deep fiords exist on the Atlantic sea-board ; that 

 of the Hudson River is traceable to the margin of the continental 

 plateau, requiring a depth of 2844: feet ; similarly the Delaware 

 Eiver valley is continued by another fiord, the floor of which is 

 now covered to a depth of 1200 feet, its continuation seaward not 

 having been ascertained ; so with the St. Lawrence and the Saguenay. 

 Similar evidence of former elevation, according to Mr. Spencer, is 

 also shown by the great depths of the American lakes. Turning 

 elsewhere, Professor Le Conte has shown that the islands south of 

 Santa Barbara and Los Angeles on the Pacific coast of the United 

 States, which are separated from the mainland, and from each other, 

 by channels from 20 to 30 miles wide, and 600 to 1000 feet deep, 

 were still a part of the mainland during the late Pliocene and early 

 Quaternary periods. Mr. Upham calls attention to the submerged 

 valleys in California, and right away to Alaska, as pointing the same 

 lesson. Travelling elsewhere again, it is impossible to doubt, if 

 we examine the biological evidence, that the Island of Ceylon has 

 been quite recently united to the peninsula of India; so with the 

 islands in the Gulf of Bengal. In a recent number of " Nature " 

 we have an account of the discoveries of the remains of an Elephant 

 in a little island in that gulf, showing that it also must have been 

 very recently joined to the mainland. We cannot explain the 

 problem of the fauna of Sumatra, except by supposing that it has 

 been very recently indeed separated from the Malay peninsula. Nor 

 do I know anyone who doubts, since the researches of Wallace, 

 that the Eastern Archipelago has been the scene of a very recent 

 dislocation and subsidence. The same kind of evidence compels 

 us to postulate the very recent sinking of the channel between 

 Tasmania and Australia ; the fauna of the two areas being so 

 conspicuously alike, while that of the former is marked by the 

 presence of more than one living animal now extinct in Australia, 

 but existing there in Pleistocene times. I might continue this 

 examination farther, and easily enlarge the number of cases, proving 

 unmistakably that at the close of the Mammoth age there was a 

 great subsidence of the earth's crust in many latitudes. 



I have argued in previous papers that it is equally clear that 

 some very important mountain chains were very rapidly, if not 

 suddenly, elevated at the same period, so that the subsidence here 

 postulated would only be the complement of elevation elsewhere. 



I do not know that the facts of such a subsidence would be 

 seriously contested provided it were granted that it were slow and 



