ELIZABETHTOWN AND PORT HENRY QUADRANGLES 93 



Again the surface must have been depressed in the postglacial 

 ur closing glacial times much below its present altitude. In no 

 other way can we account for the deposition in such great thickness 

 of the Champlain clays. Consisting as they do of fine sediment 

 which required deep and quiet waters, they indicate a decided sub- 

 mergence. They reach altitudes of 200-300 feet above tide in 

 Westport and indicate a downward journey to more than this ex- 

 tent. They must have been deposited in an arm of the sea, because 

 of the marine shells which are found in them, more especially in 

 the town of Essex, just north of the present area. A rather im- 

 pressive up and down swing of the surface is thus demonstrated. 



While the data upon the glacial deposits as here discussed have 

 been gathered when attention was especially concentrated upon the 

 hard geology and while more definite details could doubtless be 

 accumulated by special work upon this branch, yet the fol- 

 lowing record is made that the material in hand may at least become 

 available. For the latter history of the Champlain valley we have 

 the careful studies of Prof. J. B. Woodworth and those of Mr 

 C. E. Peet which are subsequently cited, and which have been 

 drawn upon in discussing these topics. 



The glacial and postglacial deposits wild be reviewed under the 

 following topics: moraines, boulders, scratches, clays and sands. 



^ Moraines. Glacial deposits in the nature of ground moraine are, 

 of course, general throughout the more elevated portions of the 

 area. The drift to the east of New Russia is very heavy and in 

 the gulch of the brook which enters the Boquet from the east it is 

 well shown. In the valley of Roaring brook i^ miles and more 

 "rem the Boquet it is also markedly in evidence. Again to the 

 -outh of Mineville and in the broad upland upon which are located 

 xvloriah Center and Moriah all the bed rock except that in the pro- 

 nounced hills is concealed. In sinking the Harmony shafts at 

 Alineville over 200 feet of boulders and clay were penetrated before 

 the work grounded on the rock. Terminal moraines or glacial 

 drift in marked lineal distribution can hardly be identified but 

 rather it seems as if a broad valley was filled up, the loose materials 

 being packed in the depressions. 



One extraordinary exhibition of boulder clay may be seen in the 

 banks of Grove brook in the southeastern corner of the map, and 

 just east of the cross roads which are a mile and a half from Lake 

 Champlain. The clay is thickly charged with pebbles up to 3 or 4 

 inches in diameter, which are almost exclusively from the Black 

 River limestone of the Ordovicic. This limestone is not of great 



