112 REPORT—1840. 
ness, and a mass of overlying tertiary sand, gravel and clay, from 
30 to 100 feet thick. The last-mentioned deposit constitutes a level 
platform, differing wholly in character from the chalk downs in En- 
gland, but the slope of the hills bounding the Seine and its tributaries, 
where the chalk crops out, corresponds exactly in character with the 
escarpments of the north and south Downs in England. There is 
however, this distinction, that the escarpments of the valley of the 
Seine, which are distant from two to four miles from each other, are 
broken at certain points by ranges of vertical and even overhanging 
cliffs of bare white chalk with flints, and by occasional needles and 
pinnacles of chalk. Mr. Lyell first refers to several natural precipices 
of chalk which occur, some on the right and some on the left bank of 
the Seine, above Andelys, or between that town and Meulan, about 
fifteen miles in a straight line from Paris. In one of these localities, 
near Bonniéres, two distinct cliffs are seen one above the other. He 
then described more particularly a great range of cliffs about two miles 
long at Andelys; secondly, another range and some pinnacles at 
Vatteville opposite Tournedos, and at Senneville; and thirdly, the cliffs 
of Elbceuf or Orival. 
In regard to the first of these ranges, it commences on the right 
bank of the river at Le petit Andelys, and includes the rock on which 
stands Chateau Gaillard. The base of the range is generally about 
fifty feet above the alluvial plain of the Seine, from which it is separated 
by a steep green slope, resembling in outline a talus of fallen debris, 
but in many places composed of solid rock. The cliffs themselves vary 
from fifty to 100 feet in perpendicular height, their continuity being 
broken by a number of dry valleys or combes, in one of which, near 
Andelys, occurs a detached rock or needle called the Téte d Homme. 
The top of this rock presents a precipitous face towards every point of 
the compass, its vertical height being more than twenty feet on the 
side of the downs, and forty towards the Seine, and the average dia- 
meter of the pillar being thirty-six feet. Its composition is the same 
as that of the larger cliffs in its neighbourhood, namely, white chalk, 
having occasionally a crystalline texture like marble, and layers of flint 
in nodules and tabular masses. The flinty beds often project in relief 
four or five feet beyond the white chalk, which is generally in a state 
of slow decomposition, either exfoliating or being covered with white 
powder like the chalk cliffs on the English coast, where, like them, the 
surface of the rock was found in some places to be encrusted with 
common salt. In regard to the origin of this superficial salt, it is 
difficult to conceive that the influence of the sea breezes can extend so 
far, as the distance is more than thirty miles from the nearest salt- 
water; but on the other hand, the author could not ascertain that any 
saline matter was contained in the chalk itself. 
Other cliffs are then mentioned, situated on the right bank of the 
Seine, opposite Tournedos, between Andelys and Pont de |’ Arche, 
where the precipices are from fifty to eighty feet high ; several of their 
summits terminate in pinnacles, and one of these in particular is so 
completely detached as to present a perpendicular face fifty feet high 
towards the sloping down. On these cliffs several ledges are seen, 
ON 
