GLACIAL LAKE WHITTLESEY. 383 



The facts seem to indicate that the first 25 or 30 feet of rise of Lake Whittlesey was com- 

 paratively rapid and that the last 10 feet was more or less slow. When the Arkona ridges 

 became submerged and the storm waves of Lake Whittlesey began to run over them with such 

 force as to tear away the material of which they were composed, the building of the Whittlesey 

 beach became correspondingly rapid. 



It is thus apparent that the distinguishing characteristics of the Whittlesey beach are in 

 close accord with the history and manner of origin of this lake. They are all such as are 

 accounted for by the raising of the lake level from the Arkona levels, which were 30 to 45 feet 

 lower and at which the waters had stood for a relatively long time and had built three strong 

 gravelly beach ridges and deltas of corresponding strength. 



Other lakes, Lake Maumee for instance, gathered nearly all their beach material by surf 

 erosion of the bottom along the shore, but none of them seem to have done so on the scale of 

 Lake Whittlesey. The writer does not recall any place in Michigan or in Ohio west of Cleveland 

 where the Whittlesey shore line has formed a notable shore cliff. There seems to have been 

 such an abundance of material that the waves were always doing constructive rather than 

 destructive work at the water fine. East of Cleveland the steepness of the lakeward slope 

 was much more favorable to the formation of shore cliffs, and some were formed between 

 Cleveland and Marilla. 



DELTAS. 



One of the exceptional characteristics of the shores of Lake Whittlesey is their general lack 

 of deltas of the ordinary type. Of course, the streams that entered this lake must have carried 

 on substantially the same work of erosion and deposition as in the preceding and succeeding 

 lake stages, but the Whittlesey shores show almost no suggestion of the delta deposits that 

 predominate all along the shores of Lakes Maumee and Arkona. 



Some prominent delta deposits, such as those on Huron River just east of Ypsilanti, on 

 Rouge River at Plymouth, and on Clinton River below Rochester, seem at first sight to be 

 correlatives of the Whittlesey beach. But these deposits have been found to belong to Lake 

 Maumee, mainly to its lowest stage. The delta of Lake Maumee east of Ypsilanti has old 

 distributaries which belong to Lake Maumee and are too high to have served at the time of 

 Lake Whittlesey. In fact, the Whittlesey beach skirts along the front of the Maumee deltas 

 without showing any notable protruding deposit belonging to its own time. 



The explanation seems to be that the valleys of the rivers were deepened and widened during 

 the time of Lake Arkona when the rivers were cutting to that lake as a base-level. Then when 

 the waters were raised to the Whittlesey beach by the readvance of the ice the lower courses of 

 all the streams were drowned and turned into dead-water estuaries. It follows that at the 

 beginning of Lake Whittlesey delta building began at the head of these estuaries and grew 

 lakeward, reaching the open shore of the lake only when the estuaries had been completely 

 filled. Thus the deltas of Lake Whittlesey are mainly inset or built within the old estuaries 

 back of the general shore line and hence formed little or no protrusions at the shore. Since 

 that time the streams have again cut down their beds and have carried away the main body of 

 their estuarine deltas. Fragments of those deltas now remain along the sides of the valleys back 

 of the Whittlesey beach as gravel terraces and are prominent in some places. They arewelldevel- 

 oped along Huron River in and below Ypsilanti. The sharply depressed, swampy little valley 

 west of Armada was made in the Arkona stage of the lake and was not refilled, its stream bemg 

 spring fed and having a very small drainage area and no flood stages to carry coarse sediments. 



In eastern Ohio along the base of the escarpment and in western New York there are several 

 delta deposits that seem to be closely related to the Whittlesey beach, but, as in Michigan, they 

 probably belong to an earlier lake stage at a slightly higher level. In New York there is one 

 delta, however, which is clearly a deposit hi Lake Whittlesey, for it buries the eastward ends 

 of the Arkona beach ridges a mile or two east of Alden. The river which built this delta flowed 

 westward along the front of the ice when the front was on the Alden moraine. It flowed in 

 a valley which had not been deepened during the time of Lake Arkona, and it is therefore an 



