Vol. 68. j GLACIAL SECTIONS K0I7ND SUDBUEY. 29' 



immediate neighbourhood of Sudbury, agree with the course of 

 events probable if a submergence preceded the deposition of the 

 Boulder Clay, and an emergence followed it. 



Discussion, 



Mr. W. Whitakee said that, when making the geological survey 

 many years ago, he found no record of the fine sections at Sudbury, 

 the finest inland sections of Drift in the Eastern Counties. These 

 sections had been constantly changing, and luckily some years later 

 the new developments M^ere noticed by Dr. Marr. It was fortunate 

 that the Author had continued the record. 



He was disposed to look on the peculiar mass of Glacial Drift 

 at the sides and bottom of the valley as belonging to a series of 

 deposits older than the Boulder Clay of the plateau, and belonging 

 rather to the ' Lower Glacial ' of Searles V. Wood, an infilling of 

 an early Glacial (or pre-Glacial) channel. 



The thickness of the deposits in some of these channels was too 

 great to allow of the explanation by land-slipping — it being greater 

 than that of any other Drift deposits in the country, as much as 

 470 feet in the valley of the Stour some miles above Sudbury. 

 Moreover, these deposits reached down to below sea-level, and 

 obviously could not result from any process going on with the land 

 at its present level. The Boulder Clay certainly was well adapted 

 for land-slipping ; but that could hardly be to the great extent 

 pointed out. Besides, the Drift-channels contained various other 

 materials as well as Boulder Clay. 



The Seceetaey read the following remarks, received from Prof. T. 

 G. Bonnet: — 



'Unfortunately an engagement on Wednesday evening, made before I knew 

 that this paper would then be read, prevents me from being present. That I 

 very much regret, since, as the Author has taken me over all the sections (as 

 I believe) described in his paper — in most cases two or three times at least — I 

 should have liked to have expressed the opinions which I have independently 

 formed. These are in full agreement with those set forth in his paper, so far 

 as I can gather from the abstract. In the Sudbury sections at about 200 feet 

 above O.I)., a quite normal 'Chalky Jioulder Clay' is seen overlying well- 

 stratified silts and sands, with occasional false-bedding. These present every 

 appearance of having been deposited under water, which was moving very 

 gently and steadily. Their stratification shows no disturbance as it approaches 

 the base of the Boulder Clay, and the latter does not in any way scoop or dig 

 into it ; but we find, not seldom, signs of a real, though rapid, transition from 

 the one to the other. 



' But, from about 180 to 100 feet O.D., that is more or less on the flanks of 

 the Stour Yalley (which the Glemsford boring has shown to be pre-Glacial) — 

 sand, gravel, and Boulder Clay (normal) show great disturbance and strange 

 associations, — masses of the last material occurring in the others, like large 

 irregular erratics. Their mutual relations are not suggestive of a ploughing- 

 up by the snout of a glacier (which, had it deposited the Boulder Clay, would 

 by this time have retreated from the district), but a downslipping of the older 

 materials and a mixture of them with coarser gravels of more local origin. 



' I may add that, sometimes in the Author's company, sometimes with others, 

 I have seen this orderly succession of silt, sand (more or less gravelly), and 

 Boulder Clay, in other parts of the Eastern Counties, and not in them only. 



