No. 5.] SPENCER — SURFACE GEOLOGY. 307 



a railway embankment after the heig-hts were cut through for 

 Desjardins canal. The elevation of the Heights is 108 feet above 

 the lake, and is the connecting link between the terraces on both 

 sides of the Dundas marsh, whose valley was excavated before 

 their deposit. Burlington beach, from 300 to 500 yards wide, is 

 about five miles long, and separates the bay from the lake in the 

 same way as the Heights separate the ba}- from the marsh, the 

 one being the counterpart of the other, when the lake stood at 

 different levels. The bay inside of the beach is 78 feet deep. 

 Neither of these beaches has been produced by sediments 

 brought down by streams and thrown up in the form of sand 

 bars, as in many modern harbors, because no important streams 

 have flowed down the Dundas valley (since the epoch of high 

 elevations at the close of the formation of the Erie clay) or do 

 now flow. More particularly is this statement proven by the 

 absence of all material belon2;inL>; to the Dundas vallev or retrion 

 drained by its streams. In the Burlington Heights there is often 

 flow and plunge bedding and slightly oblique stratification seen, 

 which dip towards the lake. Lake Ontario never freezes more 

 than a few miles from its maro'in, and even more than shore ice is 

 uncommon. Winter storms often pile the ice and contained stones 

 very high on the shores. Burlington bay always freezes over. 

 It becomes apparent that both of these ridges (the latter rising 

 only eight feet above the lake) were produced by the lake 

 action from Hudson river pebbles and sand, tran.sported by 

 coast-ice and w^aves. Any dehris of Hudson rocks found in 

 the Dundas valley below 115 feet level is very small. The 

 Jj.iurentian pebbles are no more than the few deposited from the 

 floating ice of the higher terrace epoch upon the region from 

 which the detritus came. 



The cause which determined the position of these ridges is 

 easily explained. The extension of the lake into these narrow 

 arms was frozen over during winter, not necessarily any colder 

 than that of the present time. As the north-eastern winds were 

 drivins: the coast-ice airainst the frozen barrier, it became broken 

 up and deposited its burden of stones and sand in the same way 

 that the present coast-ice with its contained stones continues to 

 increase (though very slowly) the breadth of Burlington beach, 

 aided with the action of the waves. 



Hudson River Fossils in the Jxtst two Beaches. — Abundance of 

 fossils occur in the pebbles of these beaches, at IIG feet above 



