93 
the fossils obtained are all characteristic of the Marlstone strata. The whole 
hill is but a small remnant saved from the extensive denudation which took 
place after the deposition of the Jurassie series. 
The most noticeable feature of the Knoll is the great terrace on the West 
and North-west. Ic is almost level from the foot of the upper slope to the 
brow of the lower one and fully half a mile wide in this direction, with a 
length of more than a mile. The brow of the terrace may be one hundred 
and fifty feet high in the highest part, the rise to the foot of the upper hill 
may be thirty or forty feet, and the height of the latter about three hundred 
feet, making nearly the total of five hundred feet assigned to the whole hill, 
on the assumption of which as the true height, the above proportions are 
given as approximately correct. The denuding agent here was undoubtedly 
the sea, and according to the principle laid down by Sir Charles Lyall, and 
adopted by other writers, that terraces of this nature are formed during a 
pause in the process of elevation or depression, we must suppose that the 
mean sea-level was maintained at this height for a very long period. The 
superficial material of Brent Knoll being soft clay, it is reasonable to suppose 
that the inequalities on its surface, due to the action of the sea, were made 
during the later action. We must therefore refer these inequalities, including 
this great terrace, to the last rising of the land. On this supposition, the 
long period during which the sea was cutting its way into the hill at the 
level of this great platform would be contemporary with the age of the 
highest of the Sand Dunes and the markings on the rocks on the side of 
Worle Hill, which I have supposed to be at about the same height above the 
sea-]evel. These attempts at correlation are of course only provisional, 
subject to the test of actual measurement. That the grooves and other 
markings on the hard rock must have occupied a long period, during which 
the mean sea-level must have been pretty constantly at one height, will be 
probably admitted ; and when we find, at the distance of eight miles, in- 
dubitable evidence, at about the same elevation, of the same fact, we may 
fairly consider the two sets of phenomena as contemporaneous in their 
production. 
In addition to the great terrace, which cannot fail to arrest the attention 
of the most careless, there are two sets of minor terraces which, so far as I 
know, are not mentioned by any writers. They occur on the north-east and 
north-west sides of the Knoll respectively, the former series being above the 
great platform, and the latter below it. The higher series occupy the upper 
half of the steep declivity of the hill as you descend from the summit to the 
village of East Brent. They are from fifteen to twenty in number, arranged like 
the seats in an ampitheatre. and varying in height from one to four or five 
feet, and in breadth, as nearly as 1 can remember, from one to two feet. 
Mr. Mackintosh, in The Intellectual Observer for August, 1867, has main- 
