144 PEOF. EDWARD HULL, LL.D.^ F.R.S., F.G.S., ON 



rather distant retrospect into past geological times. And 

 tirst as to its form and composition. In form it consists of five 

 disconnected, or partially connected, slabs of tabular granite, 

 large and massive in the upper part, while supported below as 

 on a pedestal by slabs of much smaller dimensions. The total 

 height from the base is, as stated by Borlase, 32 feet, and it 

 rises from a granitic platform, or flattened dome, elevated about 

 20 feet above the general surface of the moorland. At its base 

 lie large blocks and slabs of granite, and at short distances, 

 several similar monoliths of smaller dimensions. Thus the 

 Cheese wring is conspicuous from a considerable distance over 

 the moorland to the south ; and just under the south side of the 

 tor is the large granite quarry to whicli reference has l^een 

 made above. In this country of remarkable works of ancient 

 art, such as standing-stones, old crosses, druidical circles, and 

 dolmens, the Cheesewring rises pre-eminent as a conspicuous 

 work of nature. 



Composition and Mode of Formation. — In the endeavour to 

 arrive at some theory regarding the mode of formation of the 

 Cheesewring and similar isolated granitic masses, we get some 

 assistance from a view of the face of tlie quarry which has 

 been opened near its base. 



The whole mass consists of largely crystalline grey granite ; 

 and on observing the wall of rock which has been cut back 

 almost perilously near to the base of the Cheesewring, it 

 becomes clear that the rock belongs, as regards its structure, to 

 that variety known as " tabular granite." In the upper part of 

 the wall distinctly horizontal " planes of cooling " are seen to 

 have been developed, giving the mass a stratified, or bedded, 

 appearance. Granite with similar tabular structure is not 

 uncommon. I have seen it myself in the Mourne Mountains 

 in Ireland ; but the planes of division are sometimes inclined 

 to the horizon. De la Beche and Dr. Boase have recognized 

 the structure in other parts of Cornwall and Devon, and have 

 pointed out how this structure gives rise to the formation of 

 tors or earns as on Dartmoor.* Lord Avebury has also pointed 

 to ^his structure in the Logan Eock on the Cornish Coast.t 



Planes of Cooling in the Granite. — We have now to inquire, 

 what do we mean by " planes of cooling and solidification in 



* Eeport, p. 163. Similar tcrs have been developed on Kinder Scout 

 in the massive beds of millstone grit, which have a composition similar to 

 that of granite, though of course of entirely different origin. 



t Scenery of England, p. 432. 



