34 F. B. TAYLOR — CORRELATION OF BEACHES AND MORAINES. 



true interlobate deposit anywhere on the thumb beyond the Metamora 

 head. In the rest of the area here considered the ridges of the terminal 

 moraines with intervening plains of ground moraine are developed for 

 the most part in simple and regular forms. Three moraines lie beyond 

 the Metamora head and bend around on the thumb from the Saint Clair 

 valley on the east to the Saginaw valley on the west. They are best seen 

 as three distinct individuals on the eastern slope between central Lapeer 

 county and the south end of lake Huron. 



All the moraines of this region show two distinct phases. In general 

 the thumb has a smooth, flat surface, whether level or gently inclined, 

 below a contour at approximately 200 feet above the lake. This feature 

 was also noticed by Dr A. C. Lane, who joined the writer on an excur- 

 sion from Bad Axe. This level, marking a distinct plane of change in 

 the physical character of the moraines, corresponds in a general way with 

 the upper limit of submergence. Where they project above it the tops 

 of the moraines present the usual irregular rolling surface, but where 

 they lie below it they lose nearly all their irregular features, and in fact 

 are so subdued that they are often with difficulty distinguished from the 

 ground moraine. These water-laid moraines are faint as topographic 

 features, but they mark the former positions of the ice-front just as surely 

 as the hilly land-laid form. 



With respect to the configuration of the moraines, the Saginaw valley 

 is the exact antithesis of the thumb. On the latter the advancing ice 

 was held back by the obstructing high land, and its front line formed a 

 reentrant angle at each stage concave to the southwest. In the former 

 the ice pushed farther forward over the low ground along the main axis 

 of the valley, presenting a convex front to the southwest and forming 

 one of the most perfect and symmetrical ice -lobes to be found anywhere 

 on the continent. Southwest of the head of Saginaw bay the first moraine 

 back from the lake shore is water-laid and very greatly subdued, but it 

 rises gradually northeastward toward the end of the thumb and finally 

 emerges into a land-laid moraine of the normal rugged type. The other 

 moraines, though less submerged, do the same, and they all emerge also 

 in the higher region west and northwest of the bay. In the low belt 

 southwest of Port Huron these moraines also become water-laid as they 

 descend toward their apexes near Port Huron, at Detroit, and at Toledo. 



The glacial waters that gathered in the Erie, Huron, and Ontario basins 

 during the retreat of the ice-sheet underwent many changes. These 

 changes are now so far worked out that it has become possible, and also 

 very necessary, to have some clear and orderly way of designating them. 

 In falling from their highest level to the present level of lake Erie the 

 glacial waters changed the place of their outlet four or five times. At 

 each change they paused for a time, sufficient to make a distinct beach 



