474 PLIOCENE. 



Prof. W. King in 1863, and he applied the term Leda-myalis Clay.^ 

 As described by Mr. Reid, the bed is a fine false-bedded loamy sand, 

 with grains of chalk, thin seams of loam or clay, and a little gravel : 

 together from 10 to 15 feet thick. Fossils are not as a rule abun- 

 dant, but about a quarter of a mile west of Lower Sherringham an 

 Oyster-bed with O. edulis has been noticed, while at West Runton 

 a Mya-bed with j\L truticata, was described by Joshua Trimmer 

 in 1845.'* The term Mya-bed is inappropriate as a general desig- 

 nation, for the same species occurs in the position of life, at a 

 lower horizon on this coast, in the Estuarine beds (Forest-bed). 

 At West Runton, Leda nivalis, Astarte horealis, Tellina Balthica, 

 and other species occur; but the bed is rarely exposed owing to 

 debris from the cliffs. 



This fossiliferous bed was at one time grouped with the Weybourn Crag (Bare 

 Valley Beds), and it has even been termed Norwich Crag, a mistake which led to 

 the Forest Bed being regarded by some observers as beneath that formation.^ The 

 Mundesley Beds of Prof. Prestwich belong in part to this horizon, and in part to 

 the estuarine ' Forest-bed,' divisions which, Mr. Reid observes, are not always 

 to be clearly distinguished at Mundesley. (See p. 469.) 



Arctic Freshivater Bed. — Above the Leda-myalis bed there has 

 been traced in places, below the Glacial Drift, a stiff blue clay and 

 loam, with sand and gravel, i to 4 feet thick, in which, at Mundesley, 

 Dr. A. Nathorst in 1872 discovered remains of Hypmnn turgescens 

 and Salix polaris. Mr. Reid has since traced the bed at Beeston, 

 and at Ostend, near Bacton, and has obtained other Plant-remains, 

 Betula 7iana, and Hippuris vulgaris; also elytra of Beetles, Land 

 Mollusca, and remains of Spermophiltis. He terms this the Arctic 

 Freshwater Bed, and observes that the fauna and flora show the 

 first incoming of arctic land species. The bed is properly included 

 with the Glacial Deposits.* 



On the Kessingland and Gorton coast the beds beneath the 

 Glacial Drift are thus divided by Mr. J. H. Blake : * — 



Pebbly sand, etc. 

 Forest Bed | Rootlet-bed. 



and I Laminated clay and sand. 



Chillesford Series. ( Gravel and sand, with Mammalian remains. 



The lowest beds of gravel and sand contain Mammalian remains which link the 

 beds with the estuarine 'Forest Bed' of the Cromer coast, but Mr. Blake is 

 disposed to group them with the Norwich Crag. The overlying laminated beds 

 he classes with the Chillesford Clay ; they are intimately associated with the under- 

 lying strata, and merge upwards and horizontally into the Rootlet-bed. The 

 Rootlet-bed is simply a root-indented stratum, although it presents evidence, as 

 Mr. Blake remarks, of an old terrestrial surface : and he would regard it as the 

 true Forest Bed ; it consists chiefly of greenish-grey unstratified clay, and contains 



1 Geologist, vi. 160. 



2 Proc. G. S. iv. 435 ; Q. J. xiv. 171. 



^ G. Mag. 1882, p. 454; Reid, Geol. Cromer, p. 46. 



* Geol. Cromer, p. 83. 



* Explanation of Horizontal Section, Sheet 128 (Geol. Survey) ; G. Mag. 1877, 

 p. 298 ; Proc. Norwich Geol. See. i. 137. 



