THE BOWLDER-CLAY. 363 



abundant evidence of the former existence of land ice, and, from the 

 position of the stria? and the character of the bowlder-clay, the conclu- 

 sion that the ice which covered the district flowed out toward the open 

 waters of the Bay of Fundy is beyond question. 



The Bowlder-clay. 



Source of the Materials composing it. — Field investigations reveal the fact 

 that the materials composing the great mass of the bowlder-clay are ob- 

 viously derived from the rocks lying immediately to the north. These 

 rocks belong to the pre-Cambrian, Cambrian and Carboniferous Bowl- 

 ders of these systems, consisting of granites, gneisses. Lower Carboniferous 

 conglomerates, diorites or diabases, limestones, sandstones, slates, quartz- 

 ites, etc., are displayed in the debris along the foot of the bank, strewn 

 upon the beach, and also appear scattered throughout the mass of 

 bowlder-clay. Many of them are large, the gre*at majority being from 3 

 feet to 8 or 10 feet in diameter, and a considerable number are striated 

 and polished. At Negrotown point the largest bowlders are of Lower 

 Carboniferous conglomerate, the parent rock of which is from 3 to 10 

 miles to the north. 



Clay and gravel, or rock debris, constitute the principal bulk of the 

 bowlder-clay. The uppermost parts are less compacted than the lower 

 and are capped by Saxicava sands in places. This renders it permeable 

 by water to some depth, and, in those parts which contain stratified 

 seams of 'clay, springs ooze out in the hank. Owing to this fact, and to 

 the foot of the bank being continually eroded by the sea, landslips are 

 of frequent occurrence and rapid denudation of the bowlder-clay is 

 taking place. 



Its stratified Portions. — The stratified portions of the bowlder-clay arc 

 for the most part thin, and form irregular, lenticular seams in the heart 

 of the unstratified mass. They are distinctly laminated, and in some 

 places, as at the Fern ledges, the strata dip slightly northward, that is, 

 away from the shore. The material is a tough, dark red, brick-clay, 

 containing a few pebbles and bowlders, scarcely any of which exceed '.» 

 inches or a foot in diameter. These strati lied hands usually occur in 

 the middle of the bowlder-clay bank, being underlain and overlain by 

 unstratified deposits, often of considerable thickness. 



Section at the Fern Ledges. — The following section of the bowlder-clay 

 at the Fern ledges will serve to illustrate its structure and character ; it 

 was carefully measured, in descending order, a lew feet to the west of the 

 section given in my report above cited: 



