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THE ORIGIN OF DERBYSHIRE SCENERY. 



denuding agents more rapidly than the limestone, and hence 

 the steepness of these sides is easily accounted for. On 

 the eastern side the slope is much more gentle. The western 

 side is worked as a limestone quarry. The limestone is 

 massive and thickly-bedded, the upper beds being separated from 

 the lower ones by a band of clay. In working, the upper beds, 

 which are traversed by long open joints running from top to 

 bottom, are first removed down to the clay-band, which forms a 

 kind of floor, the lower beds being then worked. About 1861 a 

 landslip occurred. The upper beds had been worked back for 

 some distance, terminating in a vertical face — the jointing plane — 

 when a large mass of it slipped away, falling upon the upper floor 

 referred to above. Another and more extensive slip will be 

 remembered as occurring about the year 1880, when a house was 

 destroyed. The cause is not difificult to find. The upper beds 

 rest upon a clay floor which slopes towards the quarry. This 

 becomes wet and slippery, and the over-lying masses of limestone, 

 already naturally divided by joints, slip down and topple over. 

 The diagrammatic section, Fig. 4, will explain itself, a represetits 





the clay band. This also serves to illustrate the way in which 

 steep limestone cliffs originate. The older geologists believed 

 that precipices and cliffs had their origin in some convulsion, and 

 their writings bristle with earth-throes and catastrophes. But with 

 added knowledge the true explanation comes, and we now 



