346 
Mr. Lyeli on the Boulder Formation^ 
The freshwater strata associated with the boulder forma- 
tion above mentioned occur for the most part in patches at the 
bottom of the drift, and immediately above the subjacent chalk 
and crag, where the latter is present, as may be seen at a va- 
riety of places between Happisburgh and Runton near Cro- 
mer. The two spots where it is most largely developed are 
at Mundesley and Runton. At the latter place it underlies 
the drift and rests immediately on chalk, with the occasional 
intervention of marine crag ; while at Mundesley it occupies 
for a certain space the whole cliff, taking the place as it were 
of the drift, and appearing in part to be of contemporaneous 
origin, and in part of subsequent date and superimposed. 
Everywhere it contains the same species of shells, and as these 
are almost without exception identical with well-known Bri- 
tish species, it is evident that the entire formation of the mud- 
cliffs, whether freshwater or drift, belongs to the latest part of 
the tertiary period, the only doubt being whether it should 
not rather be considered as post-tertiary or referable to a class 
of deposits which contain exclusively shells of recent species. 
I mention at once this conclusion, because the recent origin 
of the drift adds a peculiar interest to the great derangement 
and change of position which it has undergone since its 
deposition. In no other parts of our island, or perhaps of 
Europe, are there evidences of local disturbance on so great 
a scale and of an equally modern date, for there are proofs of 
the movement both downward and upward of strata several 
hundred feet thick for an extent of many miles ; together with 
most complicated bendings and foldings of the beds and the 
intercalation of huge masses of chalk, and what is no less per- 
plexing and difficult of explanation, the superposition of con- 
torted upon horizontal and undisturbed strata. 
The line of coast in which the formations above alluded to 
are displayed was well described in Mr. R. C. Taylor’s Geo- 
logy of East Norfolk, published in 1827, and afterwards in 
Mr. Woodward’s Outline of the Geology of Norfolk, 1833. 
Both these papers are the result of a careful survey of the 
coast, and contain original observations of great merit. In 
both are given coloured sections of the clifls, from which a 
good general idea of their structure and composition may be 
derived. A memoir was also read to the Geological Society 
in January 1837, by the Rev. W. B. Clarke, in which among 
other remarks he insists on the necessity of separating the 
diluvium of Norfolk from the crag*. 
My own observations on the coast of East Norfolk were 
made first in the year 1829, and afterwards in 1839; and as 
• Geological Transactions, 2nd series, vol. v. part ii. p. 3G3. 
