Raised Bead tes of Lake Michigan. 179 



R. XII E., terain iting in a club-like expansion which rises to an elevation 

 of about 55 feet above Lake Michigan, and nearly 20 feet above the plain 

 Avhich lies east of the Des Plains river, immediately south from its terminus. 

 This bar or spit shows evidence, where opened, of having been built up 

 from the east, by successive deposits shingled on its eastern slope — which 

 dip with the slope. An excavation at Haas's gravel pit which extendfi 

 from the east side of the bar west part of the center — shows beds dipping 

 at various angles, but all toward the east — some of the beds increase in 

 thickness as they descend, but the lower bed, which is mainly sand, increases 

 in thickness toward the deeper portion of the ridge. It appears to be a sand 

 bar upon which the beach deposits were built. The following section was ob- 

 tained at- the south-side of this gravel pit, which shows the section of that 

 particular place only, for I am informed by Mr. Haas that the material of 

 tlie same bed varies greatly in coarseness within the space of a few feet, 

 but the dip of the beds is uniformly toward the east. 



1. A brown-stained gravel at the surface extending down the slope,. 

 Depth 18—30 mches. 



3. I^'ine gravel (unstained) 34 inches at top, increasing to 48 inches near 

 base. 



3. Sand beginning with scarcely any thickness at the top, but increas-- 

 ing to a thickness of 86 inches at the base of the excavation. 



4. A bed of fine gravel increasing like No." 3" from — 48 inches in- 

 tliickness. 



5. Fine gravel nearly four feet in thickness, which passes upward from 

 near the east side of the excavation assuming a nearly horizontal position 

 beneath the crest of the ridge. 



6. Sand at the bottom of the excavation becoming thicker toward the 

 liigher part of the ridge. DeiDth 6 — 36 'inches. 



Molluscan shells thought to be Unios, and also smaller shells have been 

 found in No. " 6," but none of these were at hand at the time of my visit. 

 3Ir. Haas afterwards sent an oyster shell Avhich was imbedded in No. "6,"' 

 and near it was the tooth of a ma,mmoth. If the oyster shell has not been 

 artificially introduced it suggests much as to a salt water lake. It is possi- 

 ble that the shells thought by Mr. Haas to be Unios, were salt water mol- 

 lusks. We learned of no other instance of the occurrence of molluscan re- 

 mains along this upper beach. 



Passing now to the west side of the Das Plains river we find about a 

 mile above the southern end of the bar just described a low sea cliff or lake 

 margin bearing in a curved course thi-ough Sec. 14, across the north side 

 of Sec. 22. and then northwest into Sec. 16, Tp. 39, R. XII E. This is so- 

 low a beach that it scarcely attracts notice, being m places but 2 — 1 feet in 

 lieight, but it lias the continuity and horizontality of base that marks fossil 

 lake shores. 



A tributaiy of Salt Creek lias removed the traces of the old shore west 

 from Sec. 15. The beach comes to the swale which the stream follows. 



