458 
Geology of Norfolk. 
crag of Norfolk was a more recent deposit than that of Suffolk. 
This fact was established by Mr. Charlesworth* in 1836, and in 
1837 the Rev. VV. Clarkef insisted on the distinction between 
the Norwich crag and the detrital deposits which he still called 
diluvium. 
On a re- examination of the Cromer c'ifFs in 1839, Mr. Lyell, 
who had adopted Mr. Charlesworth's classification of the crag of 
Norfolk and Suffolk, recognised the distinction between the 
Norwich crag and the northern drift, admitted the correctness of 
the order of succession established by Taylor and Woodward, | 
and the existence of freshwater beds and a forest between the 
crag and the drift. I have deemed it necessary to notice these 
facts, because the error of this eminent geologist, promulgated in 
that popular work, ' The Principles of Geology,' appears to have 
been more attractive than his correction of it in the pages of the 
* Philosophical Magazine;' § since there are still many who might 
be supposed to be cognisant of the latter who are still incredulous 
respecting the correctness of Mr. Taylor's sections. 
1 shall now proceed to a particular description of each of the 
deposits above the chalk. 
1. The Crag. 
The lowest of these is the Norwich or mammalian crag. It 
consists of a marine or fluvio-marine deposit, of very irregular 
thickness, containing the bones of elephantine and other mammals 
of extinct species, accompanied by marine shells (mixed in some 
places with freshwater shells), a very large proportion of which 
belong to existing species. Its most constant member consists of 
a collection of large chalk flints 2 or 3 feet thick, imbedded in 
a base of ferruginous gravel and sand, resting on the chalk and 
mixed with marine shells. It is in this part of the deposit that 
the bones and teeth of elephants, and other mammalian remains 
found in the crag, principally occur. In other parts it consists of 
beds of sand and gravel, varying in depth to more than 20 feet. 
I have never seen shells in it at a greater height above the chalk 
than 10 feet. Over extensive areas it is entirely free from them. 
Its boundaries in N orfolk, as far as they can be ascertained in 
consequence of the depth of covering, have been already stated. 
* ' Magazine of Natural History for 1836,' and ' Report of the British 
Association for the Advancement of Science for 183G.' 
t Transactions of the Geological Society, New Series, vol. v., p. 360, 
' On the Geological Structure of the County of Suffolk, and its Physical 
Relations with Norfolk and Essex.' 
X 'Woodward's Outlines of the Geology of Norfolk,' 1833. 
§ ' On the Boulder Formation, or Drift associated with Fresh-water 
Deposits in the Mud-ciiHs of Eastern Norfolk.' ' London and Edinburgli 
Philosophical Magazine,' Series III., vol. xvi., No. 104. May, 1840. 
