394 Mr. S. V. Wood on the Belgian Equivalents of 



Norfolk *j I showed that this lower Drift was but the deposit of a 

 bay which, subsequent to the accumulation of the Red-Crag beds, 

 advanced inland more by erosion than by depression. I also 

 attempted to show that by the time this bay had thus reached, 

 on the west, the western side of Suffolk, and on the south-west, 

 the centre of Essex, a general submergence of the country 

 terminated this accumulation of sands and gravels, and caused 

 the precipitation, alike over those beds and over the older forma- 

 tions forming the terrestrial surface of the period, of the mud 

 or clay that now occurs more or less continuously over so large 

 a portion of the British islands, and is commonly known as the 

 Boulder-clay. I also adverted to the probable great extension of 

 this lower-Drift bay in an eastwardly direction over the north of 

 Europe, from which direction the abundant pebbles of quartzite 

 occurring in the gravels appear to have been derived. 



My object is now to endeavour to show that in the Loess of 

 Belgium and the Rhine we have the extension of the upper drift 

 that in the British isles is represented by the Boulder-clay, and 

 that in the Campinian sands, spread over all the north of Bel- 

 gium, and enveloping beds of rolled stones, described by more 

 than one continental geologist, we have the precise equivalent 

 of the English sands and gravels described by me under the 

 term " lower Drift.^' 



The relationship of the Loess to the Boulder-clay seems to have 

 attracted the attention of Sir Charles Lyell ; for, in his memoir on 

 the Belgian Tertiariesf, he observes: — "In regard to the relative 

 ages of the loess and the northern drift with its erratics, the 

 only positive information which I obtained during this tour was 

 on crossing the Meuse from Maestricht to the right bank of that 

 river, opposite the city. Here, in company with M. van Rymsdyck, 

 I observed that the sands of the Limburg tertiary series were co- 

 vered by a bed of quartzose gravel with erratics, and this again by 

 loess 30 feet thick. The locality alluded to is the tableland of 

 Rassburg, near Geulem, which is about 300 feet above the Meuse, 

 and about 450 feet above the level of the sea. The erratics are 

 some of them very angular and more than 2 feet in diameter, con- 

 sisting of quartzose slate, similar to that of the Ardennes, from 

 which they are believed to have been transported. Such an in- 

 stance of the superposition of loess to a certain class of erratics 

 will not justify the conclusion that the origin of the loess gene- 

 rally was of later date than the northern drift. I should rather 

 infer from the fact here mentioned, that the transportation by 

 ice of large blocks was still going on when a part of the Belgian 

 loess was deposited ; in other words, the glacial epoch coincided, 



* Anil, and Mag. of Nat. Hist. ser. 3. vol. xiii. p. 185. 

 t Quart. Journ. Geol. Soc. vol. viii. p. 281. 



