PHYSICAL (iEOGRAPIIY OF THE REGK)X. 81 



and west as far as the narrows of Xew York Bay, which they define : sh)p- 

 ing phiins of sand stretch sovithward from the morainic liills to the sea ; 

 smaller valley moraines, formed by local glaciers, have been discerned 

 in the \Vhite Mountain region towards Littleton and elsewhere. Mounds 

 and ridges of gravel and sand, now conmionly called by the Scotch name, 

 kames, lie in the valleys and lowlands, remaining as conspicuous monu- 

 ment of the combined action of ice and water in the closing stages of the 

 glacial period : these are wonderfully developed in Maine, where, under the 

 name of "horsebacks," their height may exceed a hundred feet, and their 

 length is to be measured in miles, with hardly an interruption. 



The kames are often associated with sand-plains, probably deposited in 

 lakes temporarily held within the irregular front of the ice during its stag- 

 nant melting away, and now sometimes standing up like little plateaus, 

 higher than the valley ground about them ; such as the sand-plain in which 

 A\^aldcn Pond is contained near Concord, Mass. Sand-plains and deltas 

 also mark the shores of extinct lakes, marginal to the melting ice, where 

 the land inclined towards its retreating front : such occur in large size in 

 the lateral valleys on the eastern slope of the Connecticut valley in north- 

 ern Massachusetts and southwestern New Hampshire. The outlet of lakes 

 of this character was commonly over some low pass among the hills, and 

 the line of discharge is marked by abundant sands and gravels, as along 

 the now fiat-bottomed Greenwich valley, which led Miller's River from 

 Orange towards Palmer, v\dien its fiow direct to the Connecticut was 

 obstructed. The Florence plain, near Northampton, is a sandy delta, built 

 in a lake from which the clay beds of the middle Connecticut valley were 

 deposited after the ice had melted away. In Maine, the plains about 

 Deblois, west of Machias, cover an area of several square miles. Sand- 

 dunes are occasionally formed on these plains, as well as on the more sandy 

 river terraces, and on the sea-coast. 



More or less directly connected with the retreating ice are the great de- 

 posits of clay, sand and gravel Avith which many valleys were clogged when 

 their streams were overloaded with detritus washed from beneath the glacial 

 sheet and from the country just uncovered by its melting, and when the 

 general southward gradient of the streams was diminished by the northern 

 de])ression of the land that accompanied the closing stages of the glacial 

 period. Tt is in good part by detritus of this kind that the valley-bottoms 

 are so generally buried. 



The depression of New England here referred to, and the subsequent 

 oscillations of level have been important in determining the character of its 

 shore line. The beginning and the amount of the depression cannot be accu- 

 rately stated ; but it occurred after the period of general valley-making, it 

 was associated with the glacial period, it was greater in the north than in 

 the south, nnd it has left a considerable area that structurally belongs to 



