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ME. PEESTWICH ON THE GEOLOGY OF THE DEPOSITS 
Loess, high-level. — There is a portion of the horns of Cervus elaphus in M. Boucher de Perthes’ collection, 
from a bed of high-level clay near St. Biquier ; exact level not known. Mammalian remains are reported to 
have been found in a clay-pit on the plateau between Treport and Abbeville, but I have myself never found 
either shells or bones in such positions. 
Note. — In the original paper read in March 1862, I had introduced a discussion on the uses of the flint 
implements, treating them as fossils of this period. The subject, however, is too long and too hypothetical to enter 
upon here. I would merely remark that these rude implements may almost all be referred to flint-flakes for 
cutting and flaying, and to pointed weapons of offence and defence. There are ovoid forms to which it is difficult 
to assign a use. Some of the more spatula-shaped implements I suggested might have been used as ice-chisels : 
in arctic regions the inhabitants never travel in winter without some such instrument attached to a stick, for 
the purpose of obtaining water when required, or for making holes in the ice for fishing. I may also remark 
that in the high-level gravels the lance- or spear-headed instruments predominate, whilst in the lower-level 
gravels the simple flakes of various shapes are the commoner forms. 
§ 6. CLIMATAL CONDITIONS. EXCAVATION OF THE VALLEYS. 
I have shown, on the authority both of Continental and English geologists, as well as 
by the evidence brought forward by myself in this or in my former paper, — 
1. That certain beds of gravel, at various levels, follow the course of the present 
valleys, and have a direction of transport coincident with that of the present rivers. 
2. That these beds contain, in places, land and freshwater shells in a perfect and un- 
injured condition, and also the remains, sometimes entire, of land animals of various ages. 
3. That the extent and situation of some of these beds of gravel so much above the 
existing valleys and river-channels, combined with their organic remains, point to a 
former condition of things when such levels constituted the lowest ground over which 
the waters passed. 
4. That the size and quantity of the debris afford evidence of great transporting power ; 
whilst the presence of fine silt, with land shells, covering all the different gravel beds, 
and running up the combes and capping the summits of some of the adjacent hills to 
far above the level of the highest of these beds, points to floods of extraordinary 
magnitude. 
These conditions, taken as a whole, are compatible only with the action of rivers 
flowing in the direction of the present rivers, and in operation before the existing valleys 
were excavated through the higher plains, of power and volume far greater than the 
present rivers, and dependent upon climatal causes distinct from those now prevailing 
in these latitudes. The size, power, and width of the old rivers is clearly evinced by 
the breadth of their channel, and the coarseness and mass of their shingle beds ; whilst 
the volume and power of the periodical inundations are proved by the great height 
to which the flood-silt has been carried above the ordinary old river-levels — floods which 
swept down the land and marsh shells, together with the remains of animals of the 
adjacent shores, and entombed them either in the coarser shingle of the main channel, 
or else in the finer sediment deposited by the subsiding waters in the more sheltered 
positions. As the main channel was deepened from year to year by the scouring action 
of the rivers, the older shingle banks were after a time left dry, except during floods, 
