Bouve\] 30 [February 6, 



some light upon subordinate questions concerning the strata 

 found within its area. 



It is, perhaps, presumptuous to undertake to present even a 

 very vague idea of the condition of the surface in and about the 

 region now occupied by the rocks of the area known as the 

 Boston basin, at a period prior to their deposition ; yet it has 

 seemed to me not unwise to consider somewhat the probabilities, 

 in older to be able to form a reasonable conception of tho origin 

 of such strata as now exist in it. Upon the first study of the rocks 

 composing these strata, the questions naturally arise to the mind, 

 where did all the material composing them come from? How is 

 it possible that such a large body of boulders and pebbles could 

 have been brought so together as to make up the vast beds of the 

 conglomerate, and from whence came the immense quantity of 

 fine sediment necessary to build up the one or two thousand feet 

 of clay slates that rest upon or are interstratified with it ? 



To answer such questions by the general statement that the 

 basin was the result of erosion by the sea, that during long ages 

 in which this took place the worn-away rocks furnished the mate- 

 rial from which the conglomerate was built up, and that the fine 

 substance composing the slates was subsequently borne by rivers 

 into the basin, affords no satisfactory reply ; for it is altogether 

 inconceivable even to a mind educated to a perception of what 

 can be accomplished through long geological eras, that the eros- 

 ive action of the waves against a rock bound coast could in any 

 number of ages account for the production of such a quantity of 

 boulders and pebbles as make up the rocks mentioned, and 

 equally so, perhaps, to account for the finer material of the slates 

 without taking into view other and remote causes not hitherto 

 referred to by any writer upon the rocks of the basin, but of 

 which I design to speak. In passing I will remark that what is 

 said in this connection upon these conglomerates will apply with 

 equal force to many vast accumulations, making up like rocks of 

 other legions which have been regarded as the result of eros- 

 ive action of the sea alone. It will be my endeavor to show that 

 so far as the deposits of the Boston basin are concerned, there 

 were for an unknown period far more potent influences at work 

 towards the production of the boulders and the pebbles of the 

 conglomerates as well as for the great accumulation of the clays, 



