26 Notices of Memoirs — Mapoteca Americana. 



to 120 miles from the land, ought according to the Challenger 

 experiences to be occupied by " Globigerina Ooze," but so far from 

 the theory of distribution of oceanic deposits by depth holding good 

 in the region of the Gulf Stream, it is stated by Prof. Verrill " in 

 other localities in 1000 to 1600 fathoms, the bottom is covered 

 with, or largely composed of, hard, very irregular flattened crust- 

 like concretions of clay and iron oxide." 



In another station " a large number of pebbles and small rounded 

 boulders of granite, porphyry, etc.," occurred in a depth of 2021 

 fathoms. 



" In all our ten localities between 2000 and 3000 fathoms the 

 bottom has been ' Globigerina Ooze.' We have never met with 

 the ' red clay ' which ought to occur at such depths according to 

 the observations made in the cruise of the Challenger." 



It is rather refreshing, after all, to find that Nature works in the 

 sea as elsewhere, in varied ways, and that it is not as was generally 

 supposed that monotonous waste of "ooze" and "red clay" mathe- 

 matically arranged according to depth. 



The Challenger work, while of enormous value, has also been in 

 my opinion the source of many misconceptions and generalizations 

 really unwarranted by the extent and nature of the information 

 gathered. 



Before we can accept the dictum that all sedimentary deposits 

 arising from the settlement of matter in suspension are confined to 

 a zone not reaching over 200 miles from the land, we must have 

 many more dredgings around the continental coasts. In this excel- 

 lent work of the Albatross we have, I think, evidence that ocean 

 currents such, as the Gulf Stream, carry with them matter in suspen- 

 sion — and it is unreasonable to suppose that this must necessarily 

 be all deposited within a certain limited distance from the land — its 

 deposition being really determined by the velocity of the current. 

 1 have recently in my Presidential Address to the Liverpool Geolo- 

 gical Society given my reasons for thinking that the fine argillaceous 

 matter which is found among all the deep-sea oozes is really a me- 

 chanical deposit from the ocean waters. 



It would seem to me that while every new deep-sea dredging to 

 some extent modifies previous views, it is hardly wise to attempt to 

 draw for all time such rigid lines of demarkation between the land 

 and the ocean as some have lately tried to do. 



iTOTiciBS OIF nvciEiviionas- 



I. — Mapoteoa Geologioa Amekicana. 



A Catalogue of Geological Maps of North and South America, in 

 geographic and chronologic order, has just been published by 

 the United States Geological Survey (1884:).^ The work has been 

 prepared by Messrs. Jules Marcou and J. B. Marcou. 



The earliest map noted is one dated 1752, by J. E. Guettard, 



1 Bulletin of the United States Geological Survey, No. 7. 



