INTRODUCTION. Xill 
The fact that no trace of the mastodon has yet occurred among the abundant 
elephantine remains from the Hasboro’ Forest bed and the other beds of that series, of 
itself raises the doubt whether that animal lived during the age of the Upper Crag; since 
the Hasboro’ Forest bed, if it be not actually coeval with the Upper Crag beds contaming 
mastodon remains, is evidently separated from the latest’ of them by an interval of time 
too slight (and accompanied apparently by no change of climate) satisfactorily to account 
for the disappearance of this great proboscidean genus. The Mastodon teeth found in the 
Red and Fluvio-marine Crags, and in the Chillesford beds, have, we think, been derived 
from destroyed freshwater deposits intermediate between the Coralline Crag and the Red ;? 
while the Cetacean remains in the Red Crag have, as the author of the ‘ Crag Mollusca’ 
long since suggested, been probably derived from the destroyed Coralline Crag itself. 
Tue Forest Bens. 
‘The several deposits of this series have been distinguished in the sections by the 
letters A, B, C, D, and E. 
The Green clay of Bacton (A) occurs upon the beach about half a mile south of that 
place. It was described by the Rev. Chas. Green in 1842,° and consists of a greenish 
sandy mud, which has yielded numerous mammalian remains and freshwater Mollusca, as 
well as leaves and fragments of wood. It is associated with some blue and brown clay, 
but, like the other deposits of this series, is too much obscured by the shingle of the 
beach and the cliff talus to exhibit any section. 
The Forest bed of Hasboro’ (B) occurs at the base of the cliff, and on the beach. It 
consists of a ferruginous gravel indurated into a pan, which is associated with a bed of 
blue clay. In and on this occur the remains of a forest growth. This bed has also 
yielded abundantly mammalian remains, fir cones, and land and freshwater shells. 
Beds A and B may not improbably be identical, while the traces of this old forest 
growth are said to occur at the following other places along the beach, but they are 
usually so covered by the modern beach shingle that it is only at rare intervals they are 
exposed. ‘I'hese places are three quarters of a mile south of Overstrand Gap, at 
Mundesley,* at Trimingham, and at Cromer.’ 
1 A mastodon tooth was obtained by the late Col. Alexander from the Chillesford beds of Easton Cliff. 
2 If Mastodon arvernensis really has occurred at the base of the Coralline Crag, then the beds from 
which the remains of this animal have got into the Red and Fluvio-marine Crags may not improbably have 
been even anterior to the Coralline Crag. 
8 «Hist. Antiq. and Geol. of Bacton,’ Norwich, 1842. 
4 There is a freshwater Post-glacial bed at Mundesley (11) shown in section W, known as the insect bed, 
which might be confounded with the Pre-glacial beds of the Forest series, owing to the peculiar way it (like 
several other instances of Post-glacial beds) undercuts the Glacial beds, and is, so to speak, wedged into 
them. 
* These localities are given from information furnished by the Rev. John Gunn to the author of the 
