Rev. John Adams — On Sarsen 8tones. 201 



But it has been demonstrated that the Sarsens may be traced to 

 other beds as well as to the Lower Eocene. Mr. Whitaker, whilst 

 admitting that many of them must owe their origin to the Woolwich 

 and Eeading series, assigns those in our district chiefly to the 

 Bagshot Sands, which once overspread this end of the London 

 Basin/ but have been in great measure deniided ; and inasmuch as 

 they are often found resting on London Clay, which intervenes 

 between the Bagshot Sands and the Woolwich and Beading beds, 

 there can be no doubt of the soundness of his argument. Moreover, 

 he shows that, west of Newbury, the Lower Eocene strata gradually 

 thin off, and terminate altogether near Marlborough ; whilst there is 

 reason to believe that the Bagshot Sands overlapped them on the 

 west, and rested directly on the Chalk; and it is just on that margin, 

 over which the lowest beds never seem to have spread, that the 

 Sarsens are most abundant. His reasoning may furthermore be 

 strengthened by a circumstance which he has not mentioned, viz. : 

 that, like the Bagshot Sands in this district, the Sarsens are entirely 

 destitute of fossils ; whereas, if they had been formed only in the 

 underlying beds, this would not always have been the case, inas- 

 much as those beds are sometimes fossiliferous. 



Whatever their geological parentage may have been, it is certain 

 that they have not travelled far from their native home ; for many 

 of them have angles almost as sharp as blocks newly quarried ; and 

 specimens which have been rounded by friction are very rare.^ 



We may fairly assume then that those singular stones are the 

 remains of various Tertiary strata, which at some remote time 

 covered this district ; and that they owe their anomalous position 

 to the denudation which has dislodged them from their beds, and 

 swept away the parent sands and clays in which they were formed. 



What a strange history theirs would be, if they could unfold to us 

 the vicissitudes through which they have passed I Ages ago, long 

 before this earth was peopled by human beings, the whole of this 

 region laj^ buried beneath the sea; and the water, charged with 

 silex, here and there cemented its sandy bed into compact blocks of 

 stone. Why the process of consolidation should have gone on only 

 in particular places, and not throughout the whole mass of sand, it is 

 no easy matter to explain. But so it seems to have been. Some- 

 times stems of Fucoids were buried and sealed up. in the incipient 

 rocks, leaving a vacuum as they decaj^ed within the solid sub- 

 stance of the stone. Sometimes, too. Molluscs would bore for 

 themselves a home in their sides, just as we see similar creatures 

 burrowing in the rocks of our modern sea-coasts. How else can we 

 account for the winding root-like holes with which many of them 

 are perforated ? After they had grown old, humanlj'- speaking, in 

 their original bed, the sea withdrew from them, and left the sand 

 exposed to the wasting influences of frost and sunshine, storm and 



^ Quart. Journ. Geol. Soc, vol. xviii., p. 271. 



2 For figures and descriptions of some water-worn and rounded Sarsen stones 

 from the neighbourhood of Southampton, see Geol. Mag., 1866, Vol. III. p. 296, 

 Plate XIII. 



