4-oo The National Geographic Magazine 



the heights above the normal lake level 

 in 1895 of a bench-mark in Cleveland 

 and one at the head of the Welland 

 Canal with the heights of the same as 

 carefully determined in 1858, G. K. 

 Gilbert found that the point near the 

 northeast end of the lake rose as com- 

 pared with the point in Cleveland. 

 (Seethe National Geographic Mag- 

 azine for September, 1897.) This tilt- 

 ing of the Great Lake basins, still con- 



















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Figure 2. — Depth in Feet to Clay 



tinuing, is doubtless the cause of the 

 deepening of the water witnessed by 

 old residents and shown by gauge read- 

 ings and the submergence of stalag- 

 mites and stumps. That it was going 

 on continuously for centuries before the 

 first settlements were made on the shores 

 of the lake and before the oldest trees 

 killed by the high water of 1858 began 

 to grow we have considerable evidence 

 to show. 



As the lake has deepened it has ex- 

 tended over the lowlands about its west- 

 ern extremity, forming marshes at the 

 mouths of all the streams, making bays- 

 of some of the marshes, converting pe- 

 ninsulas into islands and islands into 

 reefs. At many places in northern Ohio 

 roads and houses have been moved south 

 on account of the encroachment of the 

 water. Many orchards have fallen into 

 the lake. The same is true of the Cana- 

 dian shore. Nowhere is there any- 

 building up at all comparable with the 

 amount of land lost. Since 1809, when 

 the first survey was made, more than 500- 

 acres have been lost in Erie county along 

 the lake and in the eastern part of San- 

 dusk}' Bay, while the enlargement of the 

 western part of the bay probably amounts- 

 to several square miles. That Put- In- 

 Bay, Kelleys Island, and the others in 

 the western part of Lake Erie were cut 

 off from the mainland in earlier centu- 

 ries by the gradual extension of the 

 lake is shown by a study of their flora. 

 All the plants that are well distributed 

 in similar soil on the mainland are found 

 also on the islands, and it is difficult. 

 to see how some of them could have 

 reached the islands while the latter were 

 separated by such wide expanses of 

 water as now exist. (For a full discus- 

 sion of this see Sandusky Flora, Ohio 

 State Academy of Science, Special Pa- 

 pers, No. 1.) 



As the water has risen it has extended 

 the lake level into the valleys of streams, 

 so that navigable water is found along 

 the lower portion of many streams 

 whose drainage area is so small that the 

 stream, if seen at an}' point above slack 

 water, might be regarded insignificant. 



In January, 1901, an attempt was- 

 made to trace out into Sandusky Bay 

 the valleys of some of the streams that 

 enter it by examining the bottom with 

 an auger suitably rigged. The plan 

 proving feasible, the work was contin- 

 ued as long as the ice was safe that win- 

 ter and the next. The bottom of the 



