. 1866.J GODWIN-AUSTEN' BELGIAN TERTIAHIES^ '249 



limestone mass in which these caves occur, and show that the dis- 

 persion of the pebbles belongs to some broader agency than river- 

 action ; whilst bed No. 3, with the remains of beaver, indicates that 

 antecedently to these conditions the valley of the Lesse was much 

 in the same state then as it is at present, or a line of river-drainage. 



Bed No. 1 of the caves may be referred to the period of the loss, 

 and 



Bed No. 2 to the Cailloua; Ardennais, which here consist of large 

 coarse shingle. 



There are no remains of any shingle banks at high levels along 

 the northern slopes of the Ardennes, which have been produced at 

 any Secondary, Nummuhtic, or Tertiary period. Nor has the Palaeo- 

 zoic series of Belgium been the source of any shingle met with in 

 the Nummulitic series of that country, the pebble beds in which 

 are wholly of chalk-flints. At low levels, as in the Tournay district, 

 there are great accumulations of quartz shingle at the base of the 

 Cretaceous series (Tourtia) ; but this is the direction in which the 

 Cailloux Ardennais are not met with. These Ardennais pebbles, 

 which have been distributed at a definite stage of the Glacial Period, 

 could not have been formed then, inasmuch as the region whence they 

 have been derived was not submerged, and the only other source 

 which suggests itself is that remarkable shingle bank which under- 

 lies the Devonian series of Belgium, in the Condroz, from Pepinster 

 to Nassogne and Couvin, along the Ardennes, namely, the '* Pou- 

 dingue de Burnot " of Dumont. 



2. Glacial Drift. — Detrital beds are in places interposed between 

 the Cam pine sands and the Crag-formation. We were conducted by 

 Captain Cocheteux to an interesting section exhibited in the outer 

 ditch of Fort No. 4. The beds consisted of loose sands, loamy sand, 

 ending with somewhat coarse sands ; at the base were pebbles of 

 white and black flint, and occasionally flint flakes (naturally formed) ; 

 there were also small white quartz pebbles ; with these were bones of 

 Cetaceans, sharks' teeth. Crag shells, and other spoil from older 

 Tertiary formations. All this material may be called local, such as 

 might have been derived from beds at no great distance ; but there 

 were also many large ragged unworn chalk-flints ; these occurred 

 for the most part in the upper portion of the accumulation. 



The Scaldesien beds were much reduced in thickness at this spot, 

 so that the Campine sands and underlying detritus lay partly on 

 green Diestien beds ; these last were also much eroded, and blocks 

 of the more tenacious portions had been cut out and caught up in 

 the detritus ; the whole surface was scored out, in one case to a 

 considerable depth. 



This accumulation in all its circumstances was very like some of 

 the lower drift-beds of Suifolk ; and enough was to be seen at this 

 place to warrant a reference to that stage of the East Anglian 

 marine drift-beds, which are represented by the sandy gravel-beds 

 below or beyond the margin of the Boulder-clay. 



Rocks of Scandinavian origin have not been met with beneath the 

 Campine sands of this part, or indeed of any part of Belgium, nor 



VOL. XXII, PART I. T 



