490 PLEISTOCENE OF INDIANA AND MICHIGAN. 



A number of channels around the south part of Grosse Isle show the same peculiarities as 

 those along the west side of the river below Trenton. Celeron Island, half a mile southwest of 

 the south end of Grosse Isle, is divided in two by a very distinct old channel 700 or 800 feet wide, 

 now a marsh about at lake level, which starts at the north end of the island and runs south along 

 its east side nearly half the length before turning southwest across it. At an earher stage, with 

 floor a little higher, this channel ran on to the south end of the island along its east side. Celeron 

 Island stands out alone between channels now carrying 14 to 15 feet of water and this fragment 

 of a distributary, so distinctly developed on the island in this isolated position, shows the re- 

 markable changes that have taken place in this part of the river. This and many of the other 

 distributary fragments lying within hah a mile or so of the river are well shown on the newer 

 charts of Detroit River issued by the United States Lake Survey. Hickory Island east of the 

 south end of Grosse Isle is separated from the larger island by a shallow channel over a quarter 

 of a mile wide. Elba Island is separated from Stone Quarry Island by one channel, and Stone 

 Quarry Island from Grosse Isle by another which is now dry. 



GROSSE ISLE NATURAL CANALS. 



Several channels on Grosse Isle are wholly different from any of those on the mainland, 

 being long and narrow and more like artificial canals than distributaries. The so-called Thoro- 

 fare is the longest and most characteristic. This heads on the east side near the north end 

 about due west of the south end of Fighting Island and runs south through the middle of the 

 island down to the ferry road near the center, where it turns southwest and enters the Trenton 

 branch of Detroit River at the Michigan Central Railroad bridge. The channel is 200 to 300 

 feet wide with no perceptible variation of width. It runs in a remarkably even course — nearly 

 a straight fine — for its whole length. 



Until a few years ago the Thorofare was almost abandoned as a fine of flow. It had only 1 

 to 3 feet of water in it, and Detroit River being a remarkably steady stream with very little 

 variation of volume, the Thorofare became choked with water plants and was a favorite breeding 

 place of mosquitoes. A few years ago the summer residents dredged a channel 4 or 5 feet deep 

 and about 25 feet wide through its whole length and a current now flows through. The Thoro- 

 fare is trenched 10 to 15 feet below the drift surface of the island. 



At a point about a quarter of a mile east of its mouth another similar canal-like channel, 

 called Frenchman Creek, branches from it and runs south to the extreme south end of Grosse 

 Isle. This channel has not yet been dredged, but remains in its natural state, a swampy bayou. 



Grosse Isle has also several much shorter channels of the same character. One branches 

 from the west side of Frenchman Creek near its south end ; another, half a mile to the northwest, 

 separates Snake Island from Grosse Isle. The first of these is swampy but almost dry, and the 

 second is still active though very shallow. Each is less than half a mile long. Another channel 

 cuts into the west side of the island opposite Trenton. Except at its north end this one is now 

 dry, but it formerly separated a small half-circular island from Grosse Isle. Another small 

 chamiel of the same kind and about a mile long cuts across the north end of the island from north- 

 east to southwest, with a, branch nearly midway to the northwest. Two more short, narrow 

 northeast-southwest channels cut across Point Hennepin. Those at the north end of Grosse 

 Isle are on low swampy ground. Narrow, canal-like channels like these appear to be found in 

 this vicinity only on Grosse Isle, though one or two short ones are said to have existed on Belle 

 Isle, above Detroit, before the improvement of that island. Some of them seem like deepened 

 creases. (See pp. 474-475, 489.) 



When the level of the waters above Grosse Isle was a little higher a small distributary 

 channel apparently led from the mouth of the south branch of Ecorse River to Monguagon 

 Creek, passed close west of Wyandotte and Glenwood, and followed Monguagon Creek back to 

 the river southwest of Wyandotte. 



