CHALK. 51 



contrast between the brilliancy of the tall milk white columns, and 

 the shaded vertical recesses between them, being then the greatest. 



No caves are found at the bottom of the Speeton cliffs, as the 

 sea is less boisterous there than at Flamborough Head, and the cliffs 

 are generally protected from its violence by a sloping mound, formed 

 by the materials that have fallen from the rock above. 



Yet, if the sea had free access to beat against the foot of these 

 highest chalk cliffs, it would not make excavations of the same form 

 as- at Flamborough Head; for here the bottom of the cliff, where it i& 

 exposed, is found to consist of another species of chalk, which we 

 may call the Lower or Coloured Chalk. This portion of the chalk 

 strata has the same grain and fracture, and tlie same absorbent qua- 

 lity, with the great body of the chalk above described; but instead 

 of assuming a massive appearance with vertical, fissures, it lies in ho- 

 rizontal, or at least flat sti-ata, generally of no great thickness, yet 

 tolerably compact ; and instead of a bright white colour, the greater 

 part is of a dull white, with a greenish, and in some places a blueish 

 tinge; while other parts are of a brick red colour, or rather of a duller 

 red, approaching to chocolate colour. The red chalk alternates with 

 the dull white, in large stripes, presenting a singular and interesting 

 appearance. The dull white chalk grows darker as it descends, pass- 

 ing into a greenish or blueish grey. 



The thickness of the coloured or lower chalk bears but a smaU 

 proportion to the great mass of the chalk rocks, as it rises only a few 

 yards in the face of the cliff, and at the places where it is seen, it 

 cannot be many yards above the shale that succeeds the chalk strata. 

 In point of hardness, there is no material difference ; yet the white 

 chalk may be called the hardest, especially M'hen compared with the 

 lowest part of the coloured chalk, which approximates in softness, 

 and other qualities, to the shale upon which it reposes. This chalk, 

 therefore, does not correspond with what is called the lower chalk 



