46 PROCEEDINGS OF THE ASSOCIATION OF 



Gray to describe a remarkable moraine in Andover, Mass. Mr. 

 Gray stated this moraine to be one mile lon^ and fifteen or 

 twenty feet in hei^lil. At the close of this paper, an animated 

 and extended discussion arose on the subject of drift. 



Dr. Jackson objected to the views of Prof. Hitchcock, as pub- 

 lished in a recent report on the Geology of Massachusetts, but 

 having had an opportunity, since those views were published, of 

 conversing freely with Prof. H., he found but little real difference 

 in their present opinions. He would, however, by no means 

 consider that we could yet form an unobjectionable theory on the 

 subject of drift, polished gi'ooves, and the transportation of erratic 

 blocks of stone. If we admit several different causes, how re- 

 markable would it be, should they be found to have acted in 

 neai'ly the same direction I Yet we cannot agi-ee upon any 

 known cause, as sufficient to explain all the facts. This country 

 exhibits no proofs of the glacial theory as taught by Agassiz, but 

 on the conti'ary the general bearing of nie facts is against that 

 theory ; for we observe nowhere in this country a general radia- 

 tion of detritus from the principal mountain ranges, although, as 

 in Rhode Island, there is a divergence from the point whence the 

 bowlders were derived. This divergence is, however, merely a 

 spreading of fifteen miles for forty in extent, and it is in the usual 

 general direction of North American drift to the southward, 

 none of the bowlders having been drifted to the north of their 

 parent bed. 



Ml'. Lyell offered some remarks on the subject of the distribu- 

 tion of bowlders and of the fmTows in the rocks, citing the result 

 of many observations in Europe. 



Mr. Redfield had, from his limited observations, been led to 

 infer that the drift of the region near New York was the joint 

 result of glacial and aqueous action, and was mainly deposited 

 during a period of increasing submergence. Mr. Redfield also 

 alluded to the agreement of the strioB of the polished rocks, and 

 of the transported bowlders and drift, with the known course of 

 the existing polar cuiTents of the ocean, in the northern hemi- 

 sphere, and suggested that this system of cuiTcnts, being essen- 

 tially the same in both hemispheres, and having its cause in the 

 dynamics of the solar system, must have operated through all 

 time, and over extensive regions, but varying in locality and di- 

 rection with the changes of outline and relative levels of seas and 

 continents, during successive geological periods. 



Some discussion then ensued on the question whetlier the 

 mounds of the western United States were the result of natural 

 diluvial causes, or the work of the Indians. 



