318 



T RE GEOLOGIST. 



and St. Biquier. Near the former place there is a bed thirty feet thick of 

 sand and gravel, but we could hear of no flint implements or fossil 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 tnis 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 Menchecourt, near Abbeville. Height of section 32 feet. 



" The gravelly clay b becomes more persistent and thicker as it slopes down 

 into the valley. ' The loam c, on the contrary, is cut off gradually by b, and 

 thins out ; its maximum thickness is from twenty-five to twenty-eight feet. 

 The sand d varies from two to eight feet, and is thickest about the middle of 

 the pit. The gravel e is of a nearly uniform thickness of half to one foot ; 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 examined 

 tut few sections, as the diggings do not go deeper than e : it appears to be 

 rather local. The gravel g was reached only in the trench opened. On the 



