T. Mellard Reade — Gulf-stream Deposits. 25 



series is not accurately delineated on the map (now somewhat 

 antiquated) of the Survey. I have not yet completed the evidence 

 so far as to warrant me in bringing it forward in a more formal 

 manner ; but, in brief, the conclusion at which I have provisionally 

 an-ived is that a far greater horizontal distribution of the Upper 

 Bagshot Sands exists, than is repi'esented on the map. The passage- 

 beds from the Middle to the Upper Bagshot strata have certain 

 jihysical characters recognizable by those who have made a special 

 study of the district ; and by these means one can make out pretty 

 well an identity, as to horizon, of the sands, etc., exposed resting on 

 the eroded surface of the London Clay, at Wokingham in one direc- 

 tion and at Aldershot in the other, with the strata exposed in the 

 railway-cuttings near Wellington College Station.^ The continuity 

 of the Upper Sands had been greatly destroyed by denudation; but 

 that is no proof that there was not once a continuous dej)Osit of them, 

 covering up completely the Middle and Lower series, overlapping 

 these, and extending itself upon the eroded sui'faces of the London 

 Clay, which must have flanked the great estuary in which these 

 Upper Sands were accumulated. All the physical characters point 

 to the deposition of the Middle and Lower series having taken place 

 under conditions which prevailed in the marshes and lagoons of an 

 extensive delta ; while the absence of all indications of such con- 

 ditions in the Upper Sands, and the presence in them in places of 

 great numbers of ferruginous casts of marine shells, seems to record 

 the fact (taking the negative evidence with the positive) that the 

 period represented by the Upper Sands was marked by a gradual 

 subsidence, which led to a much greater extension of the area of 

 deposition (in the London Basin) and an encroachment of marine 

 waters. We seem justified then in regarding the Upper Bagshot 

 Sands as a true estuarine deposit ; and it will be seen at once, that this 

 fact is of considerable practical importance as bearing upon w^ater- 

 siipply, and should be borne in mind in the selection of sites for 

 new wells, and in determining the depth to which such wells should 

 be dug, in the Bagshot District. 



V. — Gulf Stream Deposits. 



By T. Mellabd Reade, F.G.S. 



ri^HE interesting and important results of the dredgings by the 



J. U. S. Steamer Albatross ^ between July and September 1884, 



should not be allowed to pass without notice by geologists. 



In N. lat. 39° 46' 30'^ W. long. 70° 14' 45", large blocks of sandy 

 clay, some weighing 100 lbs., were brought up. " It was estimated 

 about a ton was brought up." The depth was 1060 fathoms. 



In 1168 fathoms N. lat. 38° 27', W. long. 73° 02', the dredge 

 brought up " a large quantity of masses of hard but sticky greenish- 

 blue clay, some masses varying to yellowish and buff colours." 



These depths of the sea, which are both over a mile, and from 100 



^ Compare Froe. Geol. Assoc, he. cit. 



- Marine Fauna and Deep-sea Deposits off the Southern Coast of New England, 

 by A. E. Yerrill. — Amer. Journ. of iScieuce, November, 1884. 



