12 SURFACE GEOLOGY. 



slope was to the south. In New Hampshire, the portion of the Contoo- 

 cook valley which extends through Hillsborough county was thus occu- 

 pied by a lake during a large part of the Champlain period. 



Karnes. The oldest of our deposits of modified drift are long ridges or 

 intermixed short ridges and mounds, composed of very coarse water-worn 

 gravel, or of alternate layers of gravel and sand irregularly bedded, a sec- 

 tion of which shows an arched or anticlinal stratification. Wherever the 

 ordinary fine alluvium also occurs, it overlies, or in part covers, these 

 deposits. Similar ridges of gravel have been often described by European 

 geologists, under the various names of Karnes in Scotland, Eskers in Ire- 



o 



land, and Asar in Sweden. The first of these names will be adopted in 

 this report. They have also been described by geologists in many por- 

 tions of the northern United States. In New Hampshire, kames are of 

 frequent occurrence, sometimes a single one extending in a very steep, 

 narrow ridge for miles along the lowest portion of a valley, or elsewhere 

 short and several parallel to each other, or in very irregular mounds and 

 ridges, with hollows enclosing small ponds. Their position is generally 

 along the middle or lowest part of the valleys, which are bordered by high 

 ranges of hills ; but in the south-east part of the state, in some parts of 

 Maine, and in eastern Massachusetts, where there are only scattered hills 

 with the valleys not much below the general level of the country, these 

 ridges, of smaller size than in the great valleys, are found extending usu- 

 ally north and south, without special regard to the present water-courses. 

 In the valleys of our two largest rivers, the Connecticut and Merrimack, 

 they extend long distances, but had heretofore escaped notice, owing to 

 the large amount of Icvelly stratified alluvium, forming the conspicuous 

 terraces and plains by which the underlying kames are often nearly 

 concealed. Before this later alluvium was deposited, a kame had been 

 formed in the Connecticut valley, which extended for many miles in a 

 single continuous ridge, from one hundred to two hundred and fifty feet 

 high, with steep sides ; and in the Merrimack valley a continuous series 

 of kames had been formed, consisting sometimes of a single ridge, and 

 again of several parallel to each other. Another interesting series of 

 kames extends from Saco river to Six-mile pond, and from Ossipee lake 

 south-easterly along Pine river, and by Pine River and Balch ponds into 

 Maine. The first description of any of these ridges in America appears 



