IG DESCRIPTION OF THE STRATA. 



In several parts of the coast, the alluvium is so regularly disposed 

 in beds, that it almost deserves to be termed stratified. Instances of 

 this kind appear in the cliffs between Whitby and Sandsend ; but are 

 more observable in the extensive alluvial cliffs of Holderness. Whei-e 

 this regular structure is discernible, the successive layers most com- 

 monly occur in the following order: 



1. Vegetable soil, supporting the grassy mantle which clothes 

 the surface. This valuable covering varies greatly in depth, being 

 from two or three inches to a few feet. 



2. Marl, or a mixture of marl and clay or •mould. This bed 

 is by no means regular, being in some places a few feet in thickness, 

 in others not an inch, and in many places entirely wanting. The 

 marl, in some instances, resembles pounded limestone, of a light 

 blue colour, or blueish white. In a low part of the cliff, a littl« to 

 the north of Bridlington Quay, occurs a fine white marl, containing 

 shells and fragments of shells. Among these a small shell, resem- 

 bling the Jielix ericetorum, which occurs recent on the Wolds, has 

 been detected^ A small bivalve shell is also found, which seems to 

 be a species of tellina. All the shells are very thin and brittle. 

 This white marl has the appearance of powdered chalk, mixed with 

 a little clay. The marl, both here and in other parts of the coast, is 

 often deeply penetrated by the roots of vegetables, from the soil 

 above it. 



3. Sand and Gravel. This bed is subject to as much irregular- 

 ity as the former. In some parts it is several yards in thickness; in 

 others, an inch or two ; while in others it wholly disappears. In some 

 instances, it forms only one bed ; in others, two or more successive 

 layers, alternating with marl, or clay ; especially the latter. In many 

 places, the sand is found pure, without any gravel ; in otlier spots, 

 the gravel occurs, with little or no sand. Almost all the springs that 

 issue from the cliffs have tjieir som-ces in tlie beds of sand and gravel; 



