HOLDERNESS. 
23 
occurrence is seldom witnessed, it may be proper to give the results of 
a careful examination of the attendant cii’cumstances. 
Some vague reports concerning these shells induced Mr. Smith to 
consider them as indications of the crag formation, and he expressed this 
opinion on his map of Yorkshire, (1821.) In 1824, I saw specimens 
collected by Mr. Smith and Mr. Salmond, from a situation which will be 
described ; and was immediately convinced that they were not specifically 
distinct from shells now existing in our own seas, and, therefore, felt 
unwilling to believe that they were of such great antiquity. This 
opinion was proved correct by an examination of the locality in 1828. 
About a mile south of the house of my kind friend, Mr. Stickney of 
Ridgemont, near Hedon, is a large excavation, from which gravel has 
been obtained for the neighbouring roads. The highest point of the 
hill in which the excavation is made, is thirty-six feet above the ad- 
jacent marshland, which Mr. S. informs me is five feet below the level 
of high water at spring tide, and the pit is sunk down to the level of 
the marshes. Sand, pebbles, and marine shells of comparatively recent, 
and water-worn fossils of more ancient date, are here mixed together, in 
confused and irregular layers. The pebbles and fossils may be clearly 
identified with the chalk and flint of the wolds, the lias and oolite 
of the coast near Whitby, the magnesian limestone near Sunderland, 
the coal and limestone series of western Yorkshire, as well as the grau- 
wacke and other slate rocks, with porphyry, granite, &c. of Cumberland 
and Westmoreland. 
Amidst this heterogeneous mass, which indicates such various and 
violent currents of water, it is remarkable that we find many rather de- 
licate marine shells, in tolerable perfection. Besides the strong shells 
of Turbo littoreus. Purpura lapillus, and Buecinum undatum, we have 
Mya arenaria, Tellina solidula and tenuis, Mactra subtruncata ? Cardium 
edule, * and a shell which in an imperfect state appeared to be Crassina 
* It must be owned the gravel shells are generally less truncate posteriorly, and less convex than 
the recent specimens ; hut there are variations in the form of Cardium edule, some individuals being 
more oblique than others : both varieties occur in this gravel-pit. 
