612 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



completely encircle the basin, but terminate in a successive series from higher 

 to lower in passing from northern Ohio eastward into southwestern New 

 York. He did not, however, attempt to map the moraines which were 

 formed subsequent to the Defiance moraine and work out the full correlation. 

 A part of this work has fallen to the present writer, and it is now possible to 

 speak with some assurance concerning the correlations on the south shore of 

 Lake Erie. The correlations on the north are not fully worked out, though 

 studies by Taylor have thrown much light upon them. 



In an early stage of the investigation the writer supposed that the 

 Defiance moraine was nearly the full correlative of the upper beach of 

 Lake Maumee, and that with the retreat of the ice sheet from that moraine 

 the lake level soon fell a few feet to the Leipsic or second Maumee beach. 

 This interpretation, which was published in 1892,^ was erroneous in that it 

 limited the upper beach to the district outside of the Defiance moraine. It 

 is now known to be developed as far east as Cleveland, and to be identical, 

 from Leipsic eastward to Cleveland, with the beach which in 1892 was sup- 

 posed to be the second Maumee or Leipsic beach; it has not been found east 

 of Cleveland. It has also been traced northward in Michigan to the Imlay 

 outlet, near Imlay City, and may be traced still farther north. The course 

 and known extent of the beach may be seen in PI. II. 



These later developments, while indicating that the lake held its highest 

 level long after the Defiance moraine had been formed, do not in the least 

 antagonize the hypothesis that the ice sheet constituted the limiting barrier 

 on the northeast border of the lake. The fading out of the beach near 

 Cleveland and the connection there with a moraine later than the Defiance 

 brings the strongest possible support to that hypothesis, as will be shown 

 farther on. The lowering of the lake level obviously depends upon a 

 change in the lake outlet, and, as in this case, it may have no relation to 

 the withdrawal of the ice sheet from a given moraine. 



It having been ascertained that the Defiance moraine is not the -full 

 equivalent of the upper beach of Lake Maumee, the question to be deter- 

 mined is what fraction of the upper lake stage the moraine equals. As 

 Lake Maumee occupied the district outside of the Defiance moraine while 

 the moraine was forming, it may be thought that a comparison of the 

 strength of that part of the beach with the part formed inside the inoraine 



^Am. Jour. Sci., 3d series, Vol. XLllI, pp. 284-290. 



