John Hailstone

“ Some appear so tender and so little capable of resistance, that it is difficult to conceive how they have been transported without being entirely destroyed. The prevailing material of these masses of gravel, is the pale blue or light grey variety of flint, with numerous traces of the alcyonium or other similar bodies in its substance.
According to my observation, this variety of chalk flint is not so common in the southern parts of this great chain, whilst in its continuation through Lincolnshire and Yorkshire, scarce any other is to be met with. ”

“ At their northern extremity they appear to rest upon an extensive bed of blue clay, provincially called gault. They are composed of both the varieties of chalk; of the upper containing the common black flint in abundance; and the lower or grey chalk, which contains little or none. If a line be drawn from Royston by Balsham to Newmarket, it will pretty exactly define the limits of both the varieties; the hills to the eastward being composed of the upper beds, while those to the west consist of the lower or grey chalk. ”

“ Harston hill has been examined by Mr. Warburton, Secretary of the Geological Society, who has obligingly communicated the result of his observations to me. Mine were principally made at the pit on Gogmagog hills; and as the contents of the two pits seem to differ in some respects, I have great pleasure in subjoining his remarks in the same terms as they were conveyed to me. His conjectures as to the cause of these alluvial deposits, will be read with great interest by Geologists. ”

“ In one of the pits at Reach a bed of clunch occurs, which differs from the ordinary sort and presents some remarkable appearances; the mass itself is much harder, and stuck full of concretions of a yellow indurated marl: outwardly they are of a green colour arising from the oxide of iron: they are in general kidney-shaped and of all sizes, from a hazel nut to an ordinary potatoe. The shape of the bed also deserves notice ”

“ The mass of greenstone nearest to Cambridge is found in the toadstone beds of Derbyshire, to some specimens of which the pebble No. 6, bears a close resemblance. Few of these pebbles weigh less than 8 ounces. ”

“ Pieces of basaltic rocks are sometimes found, but these are not very common. These fragments are of all sizes, and worn down in different degrees. Some are pebbles entirely rounded; others have their edges merely blunted. ”