30 CONTRIBUTIONS TO THE 



THE SAND AREA. 



Roundly speaking, Derryfield was built upon the sand. Every 

 chink, crack or crevice, every depression is filled with it ; plenum 

 is the word. The depth of this vast deposit varies from twelve 

 to twenty or more feet, and the great sloping sand-plains lie on 

 either flank of the river valley. Before the Massabesic water- 

 supply was introduced the people had mainly to rely upon wells, 

 although there were a considerable number of fine springs, some 

 of which are in use at the present day. A copious spring on 

 Hanover square has been walled in and the water conducted in 

 pipes to various points in the heart of the city, so that our citi- 

 zens have the luxury of cool spring-water throughout the warmer 

 months. An iron fountain in front of the city hall is fed from 

 this supply, where thousands of our thirsty operatives daily slack 

 their thirst. Most of the old wells are now disused or filled up, 

 but in nearly every instance the digging of each well told the 

 same story : First, an excavation though clear sand, both wind- 

 blown and stratified, then smooth and rounded cobble-stones, 

 beneath them coarse, water-bearing gravel, usuall}'- over-lying 

 clay or hard-pan. The water-worn stones rest upon the gravel 

 beneath the overlying deposits, precisely as they rested upon 

 the beds of open and flowing streams, in that far-off epoch before 

 the sand-burdened floods buried them. 



THE GREAT CLAY BEDS. 



As we have before hinted, there are along the course of the 

 Merrimack, to the northward and mainly upon the east bank, a 

 series of beds of very superior brick-clay, so extensive as to be 

 practically inexhaustible. As elsewhere, these deposits are over- 

 laid with a mantle of recent till, gravel, sand and loam. No one 

 familiar with the structure of clay can conceive of its being de- 

 posited in rapid water. These clays were laid down in the still 

 waters of ancient lakes, having been ground between the upper 

 9,nd nether^ mill-stones of the glaciers and transported to the 



