146 PROF. J. PEESTWICH ON THE RELATION OF THE 



age, whether in Belg-iiim, the North of France, or Kent. 2. The 

 Pebbles of white and rose-coloured quartz come apparently from 

 the older rocks of the Ardennes or indirectly from some of the 

 Bolderberg or Diestian beds of Belgium. 3. The subangular frag- 

 ments of flint, some retaining their natural colour, others more 

 worn and stained brown, are derived, the former directly from the 

 Chalk, the latter from an older Drift, possibly of Pliocene age ; or 

 both may have been derived, in part, from the Southern Drift*. 

 4. The worn and subangular fragments of chert and ragstone are 

 derived from the Lower Greensand of Kent and Surrey ; or also, 

 in part, possibly from the " Meule de Bracquegnies," or indirectly 

 from the Southern Drift. 5. The Large Pebbles of a white or light- 

 coloured quartzite and of a flat ovate shape, unlike the red or dark- 

 coloured round ovoid quartzites from the Triassic conglomerates, 

 may be derived indirectly from the shingie-beds of the Woolwich- 

 and-lleading Series, where I have occasionally found them ; or they 

 maj" come from quartzites of the Palaeozoic rock of the Ardennes, 

 or possibly from both. 6. The small pebbles of Lydian stone, Jasper, 

 veinstone, and worn fragments of old rocks may be derived, some 

 directly from the Ardennes, and some indirectly from the pebbly 

 beds of the Lower Greensand. 



It is obvious, from the fossils found in it in Norfolk and Suffolk, 

 that the Westleton Shingle is a marine Drift, the absence of 

 shells in its inland range being no doubt in great measure owing 

 to decalcification. Even in Suffolk, where the beds are more pro- 

 tected, it is rarely that anything more than casts are found. 



But while marine conditions extended as far as the north of Bel- 

 gium, on the south the Ardennes formed an elevated area of dry 

 land, drained by the old Mouse and its tributaries as well as by the 

 Schelde. The lower range of hills bordering these valleys above Spa 

 and Liege are often capped by a terrace of gravel derived from the 

 quartzose and schistose rocks, hard sandstones, and conglomerates 

 of the Ardennes. Pebbles of quartzite, sandstone, and white quartz 

 are consequently the common constituents of these gravels ; while 

 occasionally they contain fragments or pebbles of porphyry, slate, 

 and, very rarely, of granite. Generall}- the pebbles vary in size from 

 that of a marble to that of an eg^, though they are sometimes the 

 size of a man's head. Large blocks, but little rolled, are also occa- 

 sionally met with. 



Such was the old alluvium of the eastern tributaries of the 

 Mouse, while on the terraces of the main stream at Dinant and Namur, 

 pebbles of Triassic sandstones, of Cretaceous, Jurassic, Carboniferous, 

 and Devonian rocks are met with, but a large proportion of them 

 disappear lower down the course of the river, and only the harder 

 rock-pebbles remain in its lower reaches. On the hill above Liege 

 I noted in the flint-gravel pala'ozoic-rock pebbles very analogous to 

 those found in the Westleton Shingle, namely : — 



* To be described in Part III. 



