GEOLOGY OF FRANKLIN COUNTY 87 



now completely shallowed and filled by vegetable matter. It 

 passes thence into Upper Saranac lake, Round lake and Lower 

 Saranac lake and leaves the latter near the middle of its eastern 

 side in a wholly post-glacial channel. At the rapids at Saranac 

 village the river is only 6 miles distant from Lake Clear in an air 

 line, while by water it is from 25 to 30 miles distant. Below the 

 village the first considerable rapid is at Franklin Falls some 20 

 miles away, where the river falls 40 feet within the space of half 

 .a mile. In the 20 miles above it has fallen less than 100 feet, or 

 only about 4 feet a mile. Below the falls it flows through a gorge 

 half a mile long, with walls 100 feet high, which apparently 

 marks the channel of a small preglacial stream, or else a low 

 •divide between two small streams. Below the gorge a wide 

 marshy valley opens out, through which the river flows in a 

 beautiful series of meanders. Heavy drift-filling turns it aside 

 over the rock ledge in the gap at Unionfalls. At Clayburg, 8 

 miles below, it meets the north branch and turns abruptly into 

 the larger valley occupied by that smaller stream. Turned aside, 

 probably by depth of drift, the river encounters the ponderous 

 rock ridge at the High falls, in which it has cut a very con- 

 siderable gorge, which appears wholly post-glacial. The position 

 of the preglacial channel hereabout has not been ascertained, a 

 fairly continuous line of rock outcrops occurring to the northward 

 and many appearing to the south of the present channel. 



Beyond the High falls the valley is again broad and filled with 

 drift. At Cadyville the river is once more out of its old channel, 

 and has cut quite a gorge in the Potsdam sandstone at that point. 

 From Cadyville to the mouth of the river at Plattsburg the fall 

 is 400 feet and the distance 10 miles, giving a rate double the 

 average fall of the stream, yet the bottom of the drift-filling is 

 nowhere reached save at the pulp mill, 2 miles above Plattsburg, 

 where a long but not deep cut through the Calciferous limestones 

 has been made, and at Plattsburg itself. 



The Racquette illustrates the same features. Its headwaters 

 are in Racquette, Forked and Long lakes. In its northward 

 course from Long lake it meets and is cutting through the ridge 



