Bouve\] 34 [February 6, 



results that, from the very moment when the first depression 

 brought any part of the disintegrated rock material beneath the 

 water level the waves would commence to act upon it, bearing 

 away much of the lighter portions and acting more or less upon 

 the exposed boulders and pebbles. As the depression increased 

 the waters would spread more and more over the area until the 

 whole was covered. By the greater gravity of the rock masses, 

 the immense body of the boulders and pebbles necessary to form 

 the conglomerate would be brought together at the bottom with 

 only perhaps such portion of the other material intermixed as 

 would serve to form the cementing tie when subsequent influences 

 should lead to the consolidation of the whole; and here it is im- 

 portant to bear in mind that the matrix of the resulting rock is 

 really of the same composition as that of the enclosed masses. In 

 the deposit thus made would be the boulders and pebbles of all 

 the strata that had existed in the superincumbent rock forma- 

 tions, including those from the amygdaloid, which had been in- 

 jected as an exotic among them. 



Simultaneously with the depression of the area of the basin 

 below the sea level, there would commence a deposit of the finer 

 sediment brought down by the rivers. This may well be thought 

 to have been copious considering the character of the country 

 passed through, everywhere composed of the decayed remains 

 of the earlier rocks. Indeed it cannot be doubted that the 

 streams would be turbid with argillaceous matter, and as well 

 known, this would be immediately precipitated upon coming in 

 contact with salt water. Thus the material for the slates of the 

 basin must have steadily accumulated through long ages, produc- 

 ing the strata now existing beneath our city. Borings through 

 them near the hall we now occupy have gone over 2000 feet before 

 reaching other material, though of course the disturbance to 

 which it has been subjected and consequent plications make it 

 doubtful if the actual thickness of the slate deposited was more 

 than 1200 or 1500 feet. 



In the meantime disturbances continuing to occur at intervals, 

 and eruptions " following, both before and during the consolida- 

 tion of the strata, it is not to be wondered at that in some locali- 

 ties, after the accumulation of much slate material, portions of the 

 boulders and pebbles should be uplifted over it and so be found 



