50 History of Hingha/m. 



or generally over the surface of the neck its double character be- 

 cause obscured by the soil. Across the water of the river, on 

 Nantasket where it reappears, it shows itself double. 



THE GLACIAL PERIOD. 



A pretty full notice of the great glacier that rested over the 

 North, and the phenomena attendant upon its advance and 

 final melting away, has been given in the preliminary remarks. 

 We have now only to treat particularly of the traces left upon 

 the surface of the town by its passage. Those who bave atten- 

 tively read what has been expressed will understand that the 

 decomposed material of early rock formations making up the 

 soil of the territory of Hingham prior to the advent of the ice 

 was largely borne away by its movement, the solid rock founda- 

 tions being laid bare, whilst a large part of that which now forms 

 the bills and covers the valleys was brought forward by the on- 

 ward progress of the glacier from more northern localities. The 

 whole of the earth tbus disturbed and redistributed is known as 

 Drift. Much of it was materially changed in the transportation. 

 That directly beneath the glacier, and subjected to its enormous 

 pressure and to great friction upon the rock surfaces below, was 

 reduced to fragments, and even to the finest particles. The masses 

 of rock, too, which were borne on beneath the glacier, that escaped 

 destruction, were mostly smoothed, and often striated, like the 

 rocky strata over which they passed. The part of the drift thus 

 subjected to the crushing and grinding action of the glacier is 

 known as Till. The definition of this term " Till," as given by 

 James Geikie, the author of the exceedingly valuable work, 

 " The Great Ice Period," is " a firm, tough, unstratified stony 

 clay, with no very large bowlders, and having stones of a peculiar 

 shape." The stones referred to are such as are oblong without 

 being symmetrical in outline, and which exhibit strias most often 

 in the direction of the longest axis. Till constitutes the lowest 

 member of the drift deposits. It is the " moraine profonde, n or 

 " ground moraine " of foreign geologists, the " bowlder clay " of 

 most writers, the " hard pan " of our townsmen. It owes its 

 compact and tough character undoubtedly to the immense pres- 

 sure of the ice. 



A considerable portion of the drift which was borne in the body 

 of the glacial sheet itself, and thus escaped its grinding action, 

 upon the final melting of the ice was spread loosely over the 

 whole surface to a varying depth of from one to ten feet, and in 

 some places to a much greater thickness. It is generally com- 

 posed of gravel and sand with enclosed pebbles, and often contains 

 an abundance of bowlders of large dimensions. Like the till, this 

 upper drift is unstratified ; but neither the bowlders nor pebbles 

 in it are striated, as is the case with part of those of the former. 



