318 
THE GEOLOGIST. 
and St. Riquier. Near the former place there is a bed thirty feet thick of 
sand and gravel, but we could hear of no flint implements or fossO. bones. 
Nor were we more successful at St. Riquier, but our visit there was too short. 
" Menchecourt has been long celebrated for its mammalian remains, of which 
a large collection was made by M. Baillon. Many of these specimens were 
examined and described by Cuvier. The chalk hills rise immediately above 
the village to the height of two hundred and fourteen feet. They are capped 
to the depth of a few feet by drift-loam and clays ; the upper part of their 
slope is bare, and the lower part is covered by the deposit we have to describe, 
and t.iis passes under the recent peat and silt deposits of the valley. One of 
the largest of the Menchecourt pits is that of M. Dufour, towards the further 
end of the village, and on the right hand side in proceeding from Abbeville. 
An extensive section of the upper beds is there exhibited. The variation 
in the thickness of the strata is shown in the section of M. Lereille's pit (fig. 
3), situated on about the same level, and at the further end of the village. 
Fig. 3.— Section of a pit at Menchecoiirt, near AbbeviUe. Height of section 32 feet. 
« The gravelly clay b becomes more persistent and thicker as it slopes down 
into the vaUev. ' The loam c, on the contrary, is cut off gradually ^1 l> 
thins out; its maximum thickness is from twenty-five to twenty-eight teet 
The sand d varies from two to eight feet, and is thickest about the middle ot 
the pit. The gravel e is of a nearly uniform thickness of half to one toot ; it 
apparently does not range up to the chalk, which, at the end of M. Dufour s 
pit, has been met with directly under the sand d. Of the marl/ I exammed 
kt few sections, as the diggings do not go deeper than ^; it appears to be 
rather local. The gravel g was reached only in the trench opened. Un the 
