REVIEWS 313 



surface. At Key Largo the reef has "a probable width of at least nine 

 miles from the outer reef patches." Very great weight is given to solu- 

 tional action. Not only are the Everglades in great measure explained 

 bv it, but the sounds and mud flats between the line of keys and the 

 mainland. The disconnection is increasingly great southward, until 

 between Ke}- West and Cape Sable the mud flats and mangrove islands 

 "are all that give evidence of the former continuity of the land." 

 Thus Florida is constantly losing territory, instead of gaining it, as the 

 older views maintained. The Marquesas, formerly considered an atoll 

 built upon a raising bank, are, according to the author, merely a very 

 perfect sound, and the "lagoon" is an area of greater solution. Mr. 

 Griswold, however, does not carry the solutional theory to the extent 

 to which it is borne by the senior author. 



In manv places on the keys the elevated reef is capped by an oolite. 

 Mr. Agassiz states positively its Eeolian origin ; but Mr. Griswold, who 

 was last on the ground, says that, for several reasons, which he 

 enumerates, "the topography favors an origin for the limestone in 

 water." This guarded statement does not seem too strong for the 

 evidence presented. This oolite was traced by Mr. Griswold much 

 farther into the Everglades than any geologist has penetrated hereto- 

 fore. Mr. Agassiz interprets the formation as modified dune sand, 

 obtained from the beaches of the elevated reef, and blown inland by 

 prevailing east winds. J. Edmund Woodman. 



Correlation of Eric-Hiiron Benches with Outlets and Moraines i?i 

 Southeastern Michigan. By F. B. Taylor. Bull. Geol. See. 

 America, Vol. VIII, pp. 31-58, with map. 



In this paper there is given an account of observations in a region 

 hitherto little studied but containing evidences of a most interesting 

 glacial and postglacial historv. As stated in the title, the paper deals 

 with features observed in southeastern Michigan chiefly in the north- 

 ward projecting portion between Saginaw Bay and the lower end of 

 Lake Huron, commonly called the "Thumb." Having spent two 

 months during the past season in geological investigations in this 

 region the reviewer is prepared to lend corroborative evidence as to 

 the general conclusions of the paper and to testify to the scientific 

 acumen displayed in the interpretation of the phenomena observed. 

 The paper constitutes the first published account of detailed observa- 



