174 The Attievican Geologist. March, issm 
crop seems to be surrounded by ;i faint ten-ace. The marine 
limit may have come to this hight. but certainly went no 
higher. The clays are not noticeable above 285 feet. 
Winooski Delta. Coining to Burlington, we find increasing- 
sand terraces and much less clay, marking the approach to 
the "Winooski delta. .lust outside the city of Burlington are 
very distinct terraces to a hight of 330 feet. Beneath the 
sand of the lower terraces the clays appear, hearing shells. 
The Winooski delta is composed almost entirely of light, 
stratified sands, covering the north part of Burlington and 
Williston, Colchester to Mallett's bay, and the southwestern 
part of Essex, then narrowing to the river valley as the higher 
levels of the foot-hills of the Green mountains are reached. 
Thence river terraces, four or five in number, mainly of sand, 
extend up the river beyond Middlesex. The hight of this 
sand plain near Essex Junction is about 340 feet, the terrace 
No. 4 of the Vermont report,* while the next marked terrace, 
below that, is very distinct at 215 feet. The blue clay lies at 
nearly the same general hight under the lower end of this 
delta as in Charlotte, and it furnishes a very good brick clay 
north of Winooski Falls. As there seems to be no rock near 
the surface through the greater part of the area of the delta 
in Colchester and Burlington, the Vermont report suggests 
that the river filled up a considerable area between Colchester 
point, then an island, and the main shore, thus connecting it 
with the mainland.! This seems entirely probable. 
La Moille Delta. The La Moille formed a large delta \ very 
similar to the Winooski, making up a great share of Milton, 
southern ( Jeorgia.and northern Colchester, of two distinct lev- 
els, 270 feet and 400 feet, following up the river in terraces as 
on the Winooski. Snake and ( 'ohhle hills stood as islands at the 
highest extent of the lake, and show xevy distinct terraces to 
450 feet. In this vicinity are two interesting shell deposits. 
On the south shore of Mallett's bay a bank of stratified sands 
and clays is cut down by the road to expose a line bed of 
Saxicava, with a few Macoma shells, both in good state of 
preservation, and. in nearly every case, with the two valves 
*Voi. i, P . v.vi. 
+Ibid. 
+ Ibid., p. 142. 
