dent on a map, is equally evident in a profile of the lake basin. That part 

 of the lake east of a line between Presque Isle and the base of Long Point 

 has a relatively deep basin with a considerable area of greater depth than 

 120 feet (36.6 meters). South and east of Long Point there is a small area 

 with depths exceeding I80 feet (Sh.9 meters), within which is found the maxi- 

 mum depth of the lake. The large central section of the lake has a broad 

 flat basin with a maximum depth of 8U feet (25.6 meters). From Point Pelee 

 vesU-iard the water shoals rapidly. The entire western basin is like a shelf 

 raised well above the level of the central basin. The maximum depth recorded 

 is $h feet (l6.5 meters), but only a small part of the area exceeds 36 feet 

 (11.0 meters) in depth. In the eastern part of this section is found a num- 

 ber of islands, which, with Point Pelee on the north and Ottawa Peninsula on 

 the south, tends to make the basin distinct from the central basin toward the 

 east. The mean depth of the entire lake is 63.9 feet (19.5 meters). 



The ioresent investigation is concerned only with Western Lake Erie 

 (Fig. 3). .Mle this part of the lake is partially separated from the remain- 

 der by the oresence of the natural barriers mentioned above, the line of sepa- 

 ration is necessarily not an exact one. For the purposes of this report, the 

 line of separation is defined arbitrarily as a line which touches the Canadian 

 shore at 82* 30' west longitude, runs due south to the International Boundary, 

 and thence to the west end of Cedar ^oint. The part of the lake west of this 

 line is considered as 1/Jestern Lake Erie, and includes Sandusky Bay and Maumee 

 Bay. There is no sharp line of demarcation between Detroit River and the 

 lake; the one which has been selected is a strai^.ht line from the mouth of 

 Huron River through Bar Point lightship to the Canadian shore at Bar Point. 



The area of Western Lake Erie as defined above is 1,397 square miles 

 (3,618 squai'e kilometers). This area is reduced to 1,317 square miles 

 (3,hll square Idlometers) by the exclusion of Sandusky Bay and the five 

 largest islands. Its length, from Monroe Light to the intersection of the 

 International Boundary with 32* 30' west longitude, is hi miles (75.7 kilo- 

 meters); and its breadth, from Port Clinton Light to Leamington light, is 39 

 miles (62.8 kilometers). 



Sandusky Bay, the largest well-defined bay of the lake, has an area of 

 5U.U square miles (lUO.9 square kilometers). According to Moseley (190i;) it 

 was formed when the level at the west end of the lake raised and drowned the 

 mouth of Scindusky River. The bay is almost shut off from the lake by the 

 presence of two sand spits. Cedar Point and Sand Point. The long axis lies 

 in an east-west direction, and near the middle of its length the bay is 

 divided into two sections by Danbury Point jutting from the north shore 

 toward Martin Point on the south shore. Except where artifically deepened 

 for navigation the bay is shallow, not exceeding 13 feet (U meters) in the 

 eastern part, or 7 feet (2 meters) in the western part. The mean depth is 

 about 5 feet (1.5 meters) . Ssindusky River, the most important tiibutary 

 enters the bay near its western extremity, and a number of smaller streams 

 enter in the same locality. The mean discharge of Sandusky River near Fre- 

 mont, Ohio, for the six year period 1925-1930 was 1,050 cubic feet (29.7 

 cubic meters) per second (United States Geological Survey, 1929-1932). 



26 



