158 PEOF. E. HULL, LL.D., F.E.S., F.G.S., OX 



indicated on the Admiralty charts, we notice that opposite to the 

 river-mouths opening out on the coasts there are corresponding- 

 indentations. So also off the K'orth-east American and other 

 coasts the deep-sea contour lines run parallel with the bays and 

 river-mouths ; and moreover the valleys of the land are continued 

 by definite lines of relative depths (shown by soundings) down 

 the great irregular slopes of the sea-bottom. These lines of 

 valleys and gorges cross plateau after plateau on the ocean-floor, 

 and notch their precipitous edges witli successive gaps. These 

 valleys are traced downwards and outwards for more than 200 

 miles, and even to a depth of two or more miles below the present 

 surface of the water before they are lost on the abyssal floor of the 

 ocean. 



These successive submarine plains and plateaux were the result 

 of littoral denudation at times when the continents high above 

 water, were gradually sinking (like the smaller " Raised Beaches "" 

 during uprise of land), with such intervals of stability as allowed 

 the destructive action of the air, water, and ice to make great 

 horizontal notches along coasts and across river-channels. Con- 

 sequently certain portions of the continents have been in former 

 times at least two miles higher above the sea-level than they are 

 now. With this elevation and wider extent of land the climate 

 must have been much colder, even frigid enough for what has 

 been termed a " Glacial Age." 



Other points also are considered by the author. It was in late 

 geological times that the coasts of the Northern Atlantic Ocean, 

 both on the American and the European side, and across its 

 northern region, had an elevation high enough for an arctic 

 climate. The equatorial current could not then have had the heat 

 it now obtains by its local confinement in the torrid Gulf of 

 Mexico ; and the vicinity of the snow-laden coasts of the North 

 Atlantic would have reduced the equatorial warmth ; so that it 

 would have liad little influence in ameliorating the climate of 

 North- western Europe in the " Glacial Age." 



He also intimates that, on account of the slow and unequal 

 movements of the earth's surface, the coming and going of arctic 

 conditions must have been different at times and places ; and the 

 glaciation of one region would not be quite synchronous with that 

 of another. At all events a great part of North America, with 

 North-western Europe, had a glacial climate in late Pliocene or 

 early Pleistocene times. 



