Some Recent American Petrological Literature. 125 



reached a thickness of 20 feet, was what Mr. "Worthington Smith 

 called a contorted drift, evidently a glacial deposit, containing 

 ochreous implements swept from a distant surface and perhaps of 

 earlier date than the brick-earth specimens. The same sequence 

 with corresponding implements was observed on two sites at 

 Caddington (595-530 feet O.D. and 250-185 feet above the Lea); 

 at Round Green, one mile north-east of Luton (530 feet O.D. and 

 178 feet above the Lea); at Whipsnade, 4 miles south-west of 

 Luton (600 feet O.D. and 166 feet above the River Yer) ; and at 

 Gaddesden Row, 3 miles north of Little Heath, on the other side 

 of the Gade (544 feet O.D. and 184 feet above the Gade). Details of 

 the above discoveries may be found in Archceologia, lxvii, p. 49, and 

 in a paper about to be published by the Society of Antiquaries. 



Little Heath is 550 feet O.D., about the average level of the other 

 sites mentioned, which all have the same relation to the chalk escarp- 

 ment, and are nearly 200 feet above the nearest river. It is a 

 reasonable view that the present valleys have been cut down to 

 that extent since the brick-earth was laid down and covered with 

 glacial drift, on what are now the watersheds of several rivers. 



The brick-earth implements show the beginnings of Le Moustier 

 culture and are quite unabraded. If there is one point, on which the 

 authorities agree it is that the period of Le Moustier coincided with 

 a cold climate, some would say a glaciation. Whether this " contorted 

 drift" is connected with the Boulder-clay found in the immediate 

 neighbourhood is at present undecided, but it may be recalled that 

 James Geikie connected Le Moustier with the Boulder-clay. 



It is perhaps too soon to expect the discovery of implements at 

 Little Heath, but beds 4 and 5 seem (on paper) to correspond so 

 closely to the implement-bearing deposits to the north-east that 

 hopes may be entertained of eventual success ; so that the newly 

 opened pit may prove to have a human interest, and even a greater 

 scientific value than was recognized at the meeting. 



VII. — Some Recent American Petrological Literature. 



FOR the last few years many geologists have been unable to keep 

 in touch with the literature of their subject, partly owing to 

 pre-occupation with war work of various kinds and partly owing to 

 the spasmodic arrival in this country of non-British periodicals. 

 The following short bibliographical notes on one limited branch of 

 geological research have been put together in the hope that they 

 may be of use to those who are now returning to their normal 

 avocations, by affording them some idea of what has been done in 

 America in the way of petrological investigation during the last 

 few years. The list makes no pretence at completeness, since the 

 compiler is himself suffering from the difficulties mentioned above, 

 and the abstracts have purposely been made as short as possible, 

 giving merely the barest indication of the contents of each paper, as 

 a guide to readers who may desire to select what is of special interest 

 to them. If the idea meets with approval it is hoped to publish 

 from time to time similar compilations on other branches of geology. 



