Gushing — Geology of Clinton County. 



535 



four to six inches in diameter, were also observed embedded in the layer, as 

 well as two smaller pebbles <>t' the same character. 



Series V. Of the eleven dikes found in the township only throe call 

 for any comment. Two miles from Webster's mill, on the road west, an 

 enormous bostonite dike is exposed just north of the road. It is fully thirty 

 feet in width, has a dark reddish hue, and contains much porphyritic orthb- 

 clase, the crystals ranging up to one inch in length. Besides furnishing a 

 magnificent example of these dikes, it is also of interest for its indication of 

 the wide distribution of the bostonit.es. Just south of this dike, by the road- 

 side, is a dike of diabase (No. 96), two feet wide, which furnishes quite fresh 

 material, and is noteworthy for the strong pleochroism of its porphyritic 

 augite. One-fourth of a mile southwest of Star post office is a diabase dike 

 (No. 102), which furnishes the largest feldspar phenocrysts observed in any 

 diabase in the county. They are numerous, occur up to an inch in length, 

 breaking with lustrous cleavage faces which beautifully show the twinning 

 and complicated intergrowths of the crystals. The feldspar is close to 

 labradorite. 



Series VI. The township lies beyond the reach of the Champlain 

 deposits. It has the usual heavy glacial deposits filling the valleys. A long, 

 massive, esker-like ridge forms a conspicuous feature near Ellenburgh depot. 

 It lies right athwart the valley of the English river and has saved the railroad 

 company the trouble of constructing a trestle, or embankment across the 

 valley. It has thrown the river out of its pre-glacial course and must have 

 dammed the valley for a brief time. The river has cut but; a narrow trench 

 through it at its north end down to the level of the Potsdam in the stream 

 bed. The summit of the esker rises nearly to the level of the vallev Avails, 

 the valley being here quite wide and the sides of gentle slope. The length 

 of the esker is not known, but its width is fully one-quarter of a mile. No 

 good sections were seen, but a small cut at the base showed a coarse sand 

 matrix in which pebbles were set, these being somewhat rounded and reach- 

 ing no great size, 



Dannemora. 



This township has a more typical Adirondack character than any other 

 in the county, with the exception of Black Brook. The massive ridge of 

 Lyon mountain lies largely in it, though the summit is just over the border 

 in Saranac. The two largest lakes in the county, Chazy and Upper Chateau- 



