434? Mr. W. Ferguson on the occurrence of Chalk Flints 



sandstone were not continuous ; they graduated into each 

 other, thinned out, disappeared and reappeared most confu- 

 sedly. They were very much inclined, dipping towards the 

 south. The whole mass had much the appearance of having 

 been drifted; although from the nature of the material, and 

 the state of preservation in which the shells are found, it does 

 not appear as if it could have been transported far. The 

 sandstone is tough and soft when newly dug, but hardens on 

 exposure to air, and becomes light-coloured in drying. When 

 wet it presents a mottled appearance, the colouring being 

 greenish ; when dry, this almost disappears. The exterior 

 surfaces are quite reddened with iron. Many of the remains 

 are casts, and are on the outer surfaces of the fragments of 

 sandstone as well as in the heart of the masses. Of the re- 

 mains themselves, flattened Spatangi are most abundant. 

 Several species of Ammonites and Belemnites, as also of Car- 

 dium, Terebratula, Trochus, Solarium, Cerithium, &c, are 

 met with. In a few rare instances the shells themselves are 

 preserved. 



The following theoretical remarks are added with much 

 diffidence, nearly as they were originally delivered to the 

 Glasgow Society. 



From our brief survey of the surrounding country, we saw 

 that the prevailing rocks are the crystalline and stratified-un- 

 fossiliferous. Only in one instance does a limestone occur 

 with organics (an Ammonite) (?), which might consequently 

 belong to the secondary group. Old red sandstone occurs at 

 Aberdeen, and again (certainly) at Gamrie, but it has not been 

 positively seen at any point between, although it has been 

 supposed that it may nevertheless envelope the older rocks 

 along the coast beneath the sea-level. Oolite and Wealden 

 occur in the neighbourhood of Elgin. The distance between 

 these beds at Llanbride and the flints at Buchan cannot be 

 less than between fifty and sixty miles. Water- worn fossils of 

 the lias occur at Blackpots near Banff, but there they are 

 manifestly in a diluvial clay. The old red sandstone is the 

 newest rock that is known to occur over all Banffshire ; con- 

 sequently the whole of this county comes between the deposit 

 under consideration, and the newer formations of Morayshire. 



This greensand of Cruden is the only rock at all approach- 

 ing, in the geological sequence, the chalk beds from which the 

 flint boulders must have been derived. We are forced to 

 conclude concerning it, that if it is not in situ, it is at least 

 not far removed from it. 



The question then arises, How came the flints and greensand 

 there, and whence ? 



Mr. Hugh Miller, cautioning the young geologist against 



