ALLUVIAL COVERING m 



incrustations of moss immediately below their source, but ha^se con- 

 solidated into a kind of breccia, or conglomerate, a large portion of 

 the bed of sand and gravel through which they ooze. Masses of 

 this newly formed stone fall down occasionally on the beach. 



It is proper also to notice, that these alluvial strata, if we may 

 so term them, have in some instances undergone the same kind of 

 breaks and contortions as are seen in the rocky strata. A curious 

 illustration of this remark was observed by the authors in a part of 

 the cliff near Skipsey. The brown clay and the sand imbedded iti 

 it are there contorted and twisted in the most singular forms ; and 

 while the outline of the sand bed is deranged and bent in all direc- 

 tions, the bed itself, being composed of sand of two distinct colours, 

 brown and yellowish white, arranged in very thin layers, exhibits a 

 beautiful collection of undulating and twisted lines. A specimen of 

 these is represented in Plate I. Fig. 1. There is a strong resemblance 

 between these contorted layers of sand, and the contortions observed 

 by Dr. Mac CuUoch in the primary strata of Glen Tilt.* Another in- 

 stance no less curious is delineated in Plate I. Fig. 2. It represents 

 a portion of the cliff near Cowden in Holderness. The brown clay 

 aaa is broken and contorted; the sand and gravel bed bed, which 

 is four feet thick at b, fills up the sinuosities in the clay, particularly 

 the large gap c ; while the marl bed e e, about two feet thick, and the 

 vegetable mould at the surface ff, about a foot thick, are not at all 

 affected by the dislocations underneath them. It seems as if the 

 surface of the clay bed, before the deposition of the beds above it». 

 had, by the action of currents, or some other causes, been worn into 

 hollows or sinuosities, which the sand and gravel, subsequently 

 spread over it, completely filled up, so as to present a level surface 

 on which the marl was afterwards deposited. , 



* See Geological Transactions Vol. III. PI. 15, 16, 17, &c. 



