1861. 



NEAV ENGLAND FARMER. 



509 



wide, and 3 to 4 inches deep ; and from that 

 down to the finest scratch. In the town of Little- 

 ton, Mass., these furrows are plainly to be seen 

 on a hill of gneiss. 



In North America these furrows and stria?, with 

 but very little variation, all run in the same di- 

 rection — north and south, or a little east of south 

 — are very straight, and perfectly parallel to each 

 other. This fact proves that the drift material 

 was forced along and deposited by some solid 

 body; accordingly all the existing theories upon 

 the great problem — "What was the agency which 

 dispersed the drift, and wore down, smoothed and 

 furrowed the rocky floor over which the materials 

 moved" — suppose that ice, either in the form of 

 glaciers or icebergs, was the principal agent. 



"The iceberg theory supposes that the drift 

 country was submerged below the tops of the 

 mountains not long before the drift agency, and 

 that a polar current floated down icebergs which 

 were loaded with the materials of the drift, and 

 which, melting during their progress into a warm- 

 er latitude, strewed the drift along their course, 

 and striated the rocks at the bottom of the sea 

 by the fragments which were frozen into them. 

 This theory has the great advantage of introduc- 

 ing no more violent agencies than are now in op- 

 eration. Such a polar current now exists, bear- 

 ing icebergs, some of which are loaded with gravel 

 and boulders, into warmer regions. 



"The theory of elevations supposes that the drift 

 countries were submerged, and that their central 

 regions were subject to violent earthquakes and 

 elevations, oft repeated through a succession of 

 ages ; that these convulsions propelled over the 

 northern portions of the globe enormous waves, 

 which bore along immense icebergs of the polar 

 regions, and strewed the pre-existing loose mate- 

 rials of the surface far to the south of their for- 

 mer position ; that immense masses of such ma- 

 terials received a portion of the impulse, and act- 

 ed on the rocks beneath in the same manner as 

 glaciers. 



"The glacier ^/jeory supposes that by some caus- 

 es, which it does not profess to demonstrate, a 

 refrigeration of the climate covered the drift re- 

 gion with glaciers, and at length with a vast gla- 

 cial sheet several thousand feet thick ; that in 

 Europe the centre of origin was in the Scandina- 

 vian Mountains, (between Sweden and Norway,) 

 whence the glaciers proceeded outward in all di- 

 rections, increasing until they reached the limits 

 of the drift agency ; that in North America the 

 glaciers originated in or near the Arctic regions, 

 proceeding in a southerly direction, because in 

 this direction only were they free to move, and 

 increasing until they formed a glacial sheet 5000 

 feet thick ; that vicissitudes of climate during the 

 long periods of drift agency, caused retreats and 

 advances of the glacial sheet in directions not ex- 

 actly coincident." 



The above quotations are from Gray and Ad- 

 ams' Elements of Geology — a work which I would 

 recommend, together with the more extensive 

 works of Lyell and Hitchcock, to every one who 

 wishes to become acquainted with this important 

 and deeply interesting science. 



These theories, the mere outlines of which have 

 been given, all have their objections, but to give 

 them a satisfactory explanation, even if it were 

 possible, would require more space than belongs 



to me in this paper. It is very probable that all 

 the agencies alluded to in these theories were 

 employed at different times during the drift peri- 

 od, in bringing about the changes which then 

 took place upon the surface of the drift regions. 



During the pleistocene period, or that age of 

 the world which followed the drift period, the 

 northern part of North America remained sub- 

 merged to the depth of 400 or 500 feet below its 

 present altitude, for a great length of time ; and 

 in those parts of the country which were then be- 

 low the waters of the ocean, the original deposit 

 of drift has been essentially modified, and is now 

 called altered drift. Many of the rounded hills 

 and knolls, and long, narrow ridges of sand and 

 gravel which diversify the landscape in many 

 parts of New England, belong to this class of 

 drift. And it is probable that pebbles of all sizes, 

 and many of the smaller erratics, were then moved 

 from their original localities and rolled about by 

 the waves and currents of the ocean. But I do 

 not believe that this enormous boulder, whose 

 history, with that of its contemporaries, I have 

 faintly traced, has been moved since it was de- 

 posited here by iceberg or glacier many thousands 

 and perhaps millions of years ago. 



So much for science, speculation, and boulders. 

 Now let us continue our walk, or night will over- 

 take us in the woods. We soon entered a nar- 

 row valley through which a small brook dis- 

 charged itself into the pond. The ground was 

 quite swampy along its margin, and was covered 

 with such a thick growth of alders, elders, birch- 

 es, maples and grape vines that we could see but 

 a few feet in advance. Making our way up the 

 stream as best we could, we came to an ancient 

 dam which had been built across the brook, prob- 

 ably by some of the first settlers. What motive 

 could induce them to build a dam in the midst of 

 the forest, is not apparent, unless it was to de- 

 stroy the wood which grows on a swamp from 

 which the brook proceeds. Perhaps the swamp 

 was then a cranberry meadow, in which case the 

 motive for erecting the dam, for the purpose of 

 flowing it at pleasure, was a very sensible one. 



The valley in this place is only two or three 

 rods in width, and the dam which extends across 

 it is about 5 feet wide, and 6 or 7 feet high ; and 

 is built of earth and stones. The stream has 

 forced a passage beneath — making strange and 

 hollow, yet pleasing murmurs among the rocks — 

 and it has fallen through in several places. The 

 trees now growing upon it are of a size sufficient- 

 ly large to prove that it must have been built "a 

 long time ago." Crossing dry-shod over this 

 dam, which makes a convenient passage for pe- 

 destrians like ourselves, we next passed through 

 a dense sapling gi-owth of maple, oak and wal- 

 nut, and came to an old road which once led to 

 the pond but is now partially grown up ; follow- 

 ing this a short distance brought us to a lot of 

 8 or 10 acres in extent, which had been cleared 

 two years before. The wood which had been re- 

 moved was mostly white pine, of a large size, and 

 the little seedlings, oaks and other deciduous 

 trees which usually spring up where a forest of 

 pines has stood, were yet quite small and rather 

 scattering, but the open spaces were covered with 

 a soft kind of grass, very green and luxuriant ; 

 and where this was wanting the low blueberry 

 bushes, which had so long been buried in the 



