EVOLUTION OF IRONDEOlfQIT VALLEY. . 133 



(7) There is a notable straightening of the 440 contour south of 

 the preceding, with some cHffings north of Blossom Road, Brighton, 

 that seem to be the storm cuttings of Iroquois; (8) Just east of 

 these the second brook makes a twist around a rather shapeless 

 oravel mass north of the road, while the two drumloid promontories 

 next east are plainly notched, with another semicircular bar between 

 them, south of the road: the triangular lagoon inclosed by it has 

 been drained by an artificial ditch cut through the barrier ; 

 (9) Tracing the wave scarp eastward around the point of the hill 

 at the end of Blossom Road a wide gravel spit is found in its lee, 

 facing Kelley Road ; the elevation of this spit has been determined 

 hy Professor Fairchild to be 427.30 feet, and that of the bar at 

 Clover Street on the west of the same hill as 431 feet, which indi- 

 cates an approximate deformation of the Iroquois shoreline of two 

 and a half feet per mile in a north-south direction between here 

 and the Ridge at West Webster. 



The embayment becomes constricted at this point, where Rich's 

 Dugway road crosses the valley, and is still further blocked by an 

 island-like mass on the Penfield road next south, thus hampering 

 wave-work in its upper section. But Ira Edwards reports (1914) 

 that Iroquois beaches do exist ( 10) on the north end of the great 

 sand mass east of Allen Creek which we have taken for an esker fan 

 in Lake Dawson. This is the spot where such phenomena had the 

 best opportunity to impress themselves. 



On the east side of the embayment the beaches recommence 

 opposite where we left them, i. e. at Rich's Dugway; thence are 

 plainly traceable for a mile northward (11) as a sloping strip of 

 gravel following the smooth contours of the hillside. A consid- 

 erable delta, (12) with curiously lobate front, fills the re-entrant 

 angle of the brook then crossed ; this extends to the Float Bridge 

 road, beyond which the shore again follows the steep hillside to 

 the Ridge. 



The silt plains. If to the eye the inner shore is often elusive, 

 the silt plains are everywhere contrastingly conspicuous. They rep- 

 resent an astonishing amount of infilling of this great gulf during 

 the life of Iroquois. One has only to go down any of the "dug- 

 ways" and gaze upward at the enormous banks of sand exposed on 



