410 J. W. Spencer— Terraces about Lake Ontario. 



and in some of the hillocks, fragments of ancient beaches and 



The eastern portion of the Dundas valley is occupied by a 

 marsh, which is si [united from Burlington Bay by "Burlington 

 Heights"— a ridge which rises abruptly from the waters (of the 

 same level) on both sides, to a height of from 108 to 116 feet, 

 with the breadth on the summit of only a few hundred feet, 

 Burlington Beach, which separates the bay from the lake is the 

 counterpart of the " Heights '' and rises'eight feet above the 

 water. It is not usually more than a quarter of a mile wide. 

 Burlington Bay is excavated out of Erie clay and is 78 feet 



After this topographical description, let us now consider the 

 elevation of the beaches and terraces, and their composition. 

 (See Plates VI and VII.) 



1. The lowest beach is that forming the present lake margin 

 and rising to a height of eight or ten feet above its surface, of 

 which Burlington Beach is a portion. It is composed wholly of 

 sand and pi ttened) derived from the ruins of 

 various rocks of the Hudson Eiver formation, with a few small 

 crystalline pebbles. The pebbles are often full of characteris- 

 tic Hudson River fossils. Sometimes the rounded slabs meas- 

 ure more than a foot in length, though usually much less. 

 At the western end of the lake the present beach does not con- 

 tain iinv pebbles of the Niagara formation. The nearest expos- 

 ures of the componenl rocks arc more than twenty miles away 

 to the northward. 



2. The next terrace is 70 (to 80) feet above the lake, and 

 consists of sand,— or, in the Dundas valley, where it forms a 

 conspicuous Hat terrace, it is composed of thin-bedded loose 

 arenaceous clay, with some fine gravel along the margin. This 

 terrace in the Dundas valley is the remnant of the deposits of 

 Saugeen clay. 



3. The most conspicuous of all the terraces is that at 116 

 feet above the lake, of which '* Burlington Heights" is a por- 



Beacb, and «. the structure will be more 



fully noticed in studying its origin! alone with that of Burling- 



feet on the southern side of Dun. his, is compose.] of stratified 

 fine gravel, probably of the Hudson River formation, but with 

 large stones and semi-angular slabs (sometimes a foot and a half 

 long) composed of Niagara dolomites and other rocks of that 



5. On the northern side of the town of Dundas there is an 

 old beach with the sand and tine gravel exposed from 224 to 

 261 feet above the lake. 



