112 WORCESTER COUNTY HORTICULTURAL SOCIETY. [1893. 



and gravel on the surface varied from, so to say, thirty or forty feet in 

 thickness. Rivers had washed it, and in tropical and warmer tem- 

 perate regions the growth and decay of vegetation had been sufficient 

 to produce organic acids in such quantity that more complete pulver- 

 izing of the rocks had occurred than in colder regions. In the north 

 soils were deep enough for cultivation, but the detritus was coarse and 

 unfit for finer plant life. Then came the Glacial Period and the ice 

 movement. The great sheet of ice flowed southward, pushed for- 

 ward and mixed the detritus already made by oxidation and wave and 

 river action, and beneath the mighty mass bolted much of it to the 

 fineness of flour. Once it was supposed that the great fertility of the 

 Genesee valley in Western New York, a region fifty years or more 

 ago accounted the garden of the United States, was due to the lime- 

 stones which lay underneath it, — that the disintegration of these had 

 made the soil so durable that wheat could be raised forty successive 

 years on the same land without much exhausting it. But later investi- 

 gation has shown the fact to be that glacial agencies have borne the 

 soil from the disintegrated limestones and shales farther north, mixed 

 them and spread them all over the central and western parts of the 

 State. But beyond this, over nearly the whole region from Maine to 

 Dakota and as far southwards as the Ohio river, the glacial ice sheet with 

 its graving tools of boulders and pebbles frozen into its sockets has 

 eroded from the solid bed-i'ocks over which it mounted as much more 

 material for soil as before existed. Indeed, Prof. Crosby of Boston 

 has estimated that the fresh rock-meal deposited in all the Boston 

 basin, or everywhere within twenty or more miles from that city, at 

 the end of this epoch was twice the amount which had previously been 

 formed. Certainly the force which furrowed Kelley's Island in Lake 

 Erie fifteen feet deep, which ploughed the iron-like trap of Mt. 

 Holyoke to the depth of many inches, which decapitated Monadnock, 

 and swung itself a thousand feet in thickness over Mt. Washington, 

 which transported on its bosom boulders of many tons weight from 

 one to a hundred miles was adequate to the task of planing a conti- 

 nent. Of this we have certain and abundant evidence within the con- 

 fines of our own city. A major part of the loose soil and gravels, 

 and, if I mistake not, all the clay banks in the vicinity of Worcester 

 are glacial deposits, though some of these have been changed, and 

 here and there overlaid by river deposits. The bed-rocks wherever 

 freshly disrobed of their earth mantle, as on the slopes of Millstone 

 and Chandler Hills, and Mt. St. James, and over the whole crest of 

 Oak Hill, are planed or scored in parallel lines running nearly north 



