476 Correspondence — Prof. J. PrestivicJi. 



the Midland Bunter must have extended over a large part of 

 Staffordshire (interruptions being mainly due to faulting or denu- 

 dation), and they have trespassed on the neighbouring counties. 

 Their thickness sometimes come near, if it does not exceed, 300 feet, 

 and very commonly is over 100 feet. 



(2) How he explains the fact that the Triassic pebble beds 

 present such a close resemblance to the nagelfluTi of the Alps, and 

 to the great gravel beds of later date which overspread the low- 

 lands on both sides of that chain, while it is difficult to find a 

 parallel for them among beds undoubtedly marine. I asked these 

 questions in 1890, but failed to obtain an answer, so I am obliged 

 to repeat them. T. G. Bonney. 



THE SOUTHEEN DEIFT. 



Sir, — In this month's number of the Journal of the Anthropological 

 Institute, p. 45, there is a statement of so misleading a character 

 that I cannot pass it over without comment. In speaking of the 

 Hill Gravels of Berkshire, Mr. 0. A. Shrubsole says : '•' this ex- 

 tensive deposit is composed of the Southern Drift of Phillips 

 and Prestwich." Anyone reading this would suppose, as he gives 

 precedence to the late Prof. Phillips, to whom I have not referred 

 in my paper on the Southern Drift, that I had failed to make 

 acknowledgment to him as the discoverer thereof. Such an im- 

 pression I am anxious at once to remove. I was at a loss to conceive 

 what foundation Mr. Shrubsole had for this statement. On turning 

 to Phillips' " Geology of Oxford and the Valley of the Thames, 

 1871," 1 find at p. 460 the following paragraphs. After speaking 

 of the " operation of a great flood, a deluge, coming from the north, 

 north-west, and north-east," bringing down spoil of the Midland 

 Counties into the Valley of the Thames at Maidenhead and at 

 Kensington, Prof. Phillips says : " Looking at the distribution of 

 foreign drift in the country under review, we find evidence of 

 abundant currents from the north, which brought plenty of gravels 

 on the western side, but no Boulder-clay ; and plenty of Boulder- 

 clay with some gravels on the eastern side ; while in the middle 

 space there are traces of currents from the south transporting flints 

 and Sarsen-stones." A diagram accompanies this description showing 

 flints and Sarsen-stones from the Chalk hills, apparently of Kent, 

 sti'iking in between the north-west and north-east drifts. He then 

 goes on to say how this might have been effected by the agency of 

 ice. This is all that Professor Phillips says of the composition of 

 this drift. He does not even mention the term " southern " in the 

 text ; but in the index attached to the word " drift " are the words 

 "northern" and "southern," used, I presume, merely as antithesis. 

 No definition of age nor superposition is attempted : and, be it 

 observed, surrounded as the Thames basin is on all sides by Chalk 

 ranges, flints and Sarsen-stones are of themselves no sufficient 

 evidence of direction of their source. 



Long before I had formulated my ideas respecting the Southern 

 Drift, I often had the opportunity of discussing with my old friend 



