590 REVIEWS 



nearly filled with a much softer deposit than the till of which the banks and the bor- 

 dering submerged plain is composed. This evidence is in harmony with several lines 

 noted by the author in other publications in support of the view that the water area is 

 being extended at the west end of the Lake Erie basin, the principal lines being sub- 

 merged stalactites in caves, submerged areas formerly covered by forests, the testimony 

 of the flora of the islands to a former connection with the mainland, the observations 

 of old residents as to encroachments made in the past eighty years, and gauge read- 

 ings at Erie and elsewhere that show the water to have been lower at times in the first 

 half of the nineteenth century than it has been since. In explanation of this exten- 

 sion of the lake the author cites the results of Gilbert's studies which indicate that a 

 northward differential uplift is now in progress. 



Pierce, S. J. The Cleveland Water Stipply Tunnel. Am. Geol., Vol. 



XXVIII, pp. 380-85, 1901. 



A tunnel extended 26,000 feet under Lake Erie with a depth of 100 feet below 

 lake level at the shore and no feet at the lakeward end is entirely through a stratified 

 blue clay with thin partings of fine sand. The sand partings are from one-sixty-fourth 

 to one-eighth of an inch thick, and separate the clay bed into layers three-fourths to 

 one and a half inches thick. The bedding is generally horizontal, but shows some 

 wave action, cross-bedding, and folding. Chemical analyses of the sand and the clay 

 show them to be strikingly similar in composition where samples were taken close 

 together, but some variation is found in different parts of the tunnel. Fragments of 

 rock up to eighteen inches in diameter are imbedded in this deposit, and they vary 

 greatly in the amount of water wear and glacial scratching. Many are syenites and, 

 with the exception of a moderate number of local shales and sandstones, the rocks are 

 of distant derivation. 



The paper concludes with an account of test borings made near the mouth of the 

 Cuyahoga that suggest to the author a continuation of the river channel under Lake 

 Erie, but this is 85 feet below the surface of the lake and may admit of a very differ- 

 ent interpretation, the data being, in the reviewer's opinion, insufficient to warrant 

 definite conclusions. The preglacial valley of the Cuyahoga has been found, by 

 borings made by the author, to have a bed about 450 feet lower than the surface of 

 Lake Erie, or not far from 125 feet above tide. 



Blatchley, W. S.. and Ashley, G. H. The Lakes of Northern Ittdiana and 



Their Associated Marl Deposits. Twenty-fifth Rept. Geol. Survey 



Indiana, pp. 31-233, 248-321, Pis. I and VI-XII, Figs. 1-70, 1901. 



Lakes are classified as kettleholes, channel, and irregular depressions. The 



agencies of extinction mentioned are : material brought in by streams and springs, 



decrease of water supply from seepage, artificial drainage, and, most important of all, 



replacement by muck formed through the decay of aquatic vegetation. 



Marl deposits occur chiefly in the three northern tiers of counties. They range 

 in area from a fraction of an acre up to about 1,700 acres, but the majority fall below 

 100 acres. The thickness is known to reach 45 feet, and a large majority of the lakes 

 appear to have a deposit 20 feet or more in depth. The marl is thought to be depos- 

 ited from spring water through the loss of carbon dioxide caused in three ways : (i) by 



