184 Wisconsin Academy of Sciences^ Arts and Letters. 



like prolongation of the western beach line down the north side of the river 

 is fully li miles. This inward curving of the southern ends of the two 

 beach lines diminishes the distance between the ridges one-half, but still 

 leaves so wide a gap that the connection of the eastern ridge with the ser- 

 ies of raised beaches is not yet satisfactorily determined. 



No good exposure was found in the western beach line, but the eastern 

 has a diagonal exposure of its whole vertical section at the lake bluff. Por- 

 tions of the plain which lies immediately west of this ridge are covered 

 with peat, and we find that at the exposure along the lake a peat bed 

 which lies near the surface just west of the ridge, passes under the ridge 

 as shown in the following section and description. 



Section near beach line beneath plain which borders it on the west: 



1. Soil and gray sand 13-15 inches 



2. Peat 2-3 inches 



3. Gravelly sand 6-36 inches 



4. Yellow pebbly clay, vei'y calcareous 11-12 feet 



The clay No. " 4 " assumes a bluish cast near the bottom, just above the 

 water's edge. Its upper surf ace is eroded, and No. "3" has filled uj) the 

 old channels or irregularities in its surface. It is for this reason that it 

 varies so much in depth. No " 3 " contains blocks of limestone 8-10 inches 

 in diameter, but the majority of its jaebbles are small. 



As we go from this exposure through the exposed section of the beach, 

 we find the sand which overlies the peat bed in the above section, increases 

 in thickness as soon as the ridge is entered. When it attains a thickness of 

 about five feet, a coarse gravel and cobble appears above the sand. Thisv 

 cobble-gravel is a thin bed at first, but increases to a thickness of 11 — 12 feet 

 beneath the highest part of the beach ridge, and has here layers of sand in- 

 terstratified with it. The bed of sand which lies beneath this gravel has 

 a depth of some ten feet or more beneath the deepest portion of the ridge. 

 It is underlain by a peat bed, the continuation of the peat which lies near 

 the surface west of the ridge, as is shown in the above section. The peat 

 bed has slight breaks in it beneath the beach ridge, but can be easily fol- 

 lowed at a quite definite horizon entirely through it. It is 3 — 6 inches in 

 thickness. It contains pieces of mangled wood beneath the higher portions 

 of the ridge. Between this peat bed and the yellowish blue till which 

 forms the base of the exposure, there is a gravelly sand 6 — 18 inches in 

 depth. The till rises about 12 feet above the level of the lake. The eleva- 

 tion of the crest of the beach ridge is about 35 feet above Lake Michigan. 



The jpeat bed is found along the lake shore east of this beach, near the 

 surface, as it is west of the beach. The beach appears, therefore, to have 

 been built upon a suboierged land surface. There is probably significance 

 in the fact that the peat only extends a few rods west from the beacli 

 ridge, but fringes it on this border for several miles. East of the beach the 

 peat occupies a considerable portion of the interval between this and a 



