GEOLOGY AND ARCHEOLOGY OF CORNWALL AND DEVON. 263 



It is probably very unusual, and, no doubt, most undesirable 

 to bring a paper before a society for the purpose, not of communi- 

 cating, but of soliciting information : to have, in short, no higher 

 aim than that of calling attention to desiderata and unsolved pro- 

 blems. But, be this as it may, my present object is to ask my 

 friends in Cornwall to devote attention to certain questions, in- 

 teresting in themselves, and calculated to throw light on certain 

 points, more or less obscure, in the geology and archseology of 

 Devonshire. 



Joints: — Thanks to the President of the Royal Institution of 

 Cornwall, and others, it has long been known that the granites 

 and older rocks of Cornwall and Devonshire are traversed by 

 joints which pass in definite directions through all the rocks alike, 

 whatever their age or material. In the latter county, at least, 

 they form two principal systems, which, speaking roughly, may 

 be called the " east-ancl-west joints " and the " north-and-south 

 joints." It cannot be doubted that they are superinduced, that all 

 those of either system are of one age whatever the rock they 

 traverse, and that the age of each system must be less than that 

 of the most modern rock they pass through. Now, as we know 

 that the granites of the two south-western counties are more 

 modern than the great Coal period, it follows that both the east- 

 and-west and the north-and-south joints came into existence in 

 post-carboniferous times. To this extent, I believe, the joint 

 phenomena everywhere concur ; ^ut beyond it, there is not, so far 

 as I am aware, any evidence, save in one limited locahty. 



The excepted district is the southern shore of Torbay, where 

 the two systems of joints intersect the Devonian limestone, and one 

 another. In the same locality the comparatively modern New 

 Red Sandstones, or Triassic rocks, are well developed — the form- 

 ation to which the well-known red colour of the cliffs of south- 

 eastern Devonshire is due. Now, it happens that, instead of being 

 in contact, as they all were originally and many of them are still, 

 the walls of many of the joints of both systems are some distance 

 apart, and the spaces between them are filled with New red sand- 

 stone dikes, of which those running north and south are of a 

 slightly, but appreciably, darker red than those having an east- 

 and-west direction. It is not possible therefore to avoid the con- 



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