Correspondence. 379 
A Geologist may now be able to ascertain whether there is a real 
fault between the High Tor and Masson Hill, or whether the fault 
be only apparent through the falling down of the strata on the 
western side of the great rent to which the Tor originally owed its 
existence. A part of the second or under bed of toadstone may now 
be seen near Mr. Stevenson’s Paint-works, under the High Tor. 
Shreds or fragments of raised beaches may be recognized behind 
Matlock Bath and other parts of the valley; but the finest speci- 
mens of raised beaches, of dimensions admitting of being explained 
by ordinary earthquakes, may be traced to the south of Cromford, on 
the right hand of the Cromford and Wirksworth Road. The Black 
Rocks to the left of the road, at a much greater elevation, reveal in 
a very impressive manner the action of oceanic waves, tides, and 
currents. The angles of the jointed blocks of hard Miilstone- 
grit, and in many instances the fractured surfaces, appear as if they 
had resisted atmospheric action or weathering for thousands of 
years. Furrows, a few inches in depth, have in some places evidently 
been worn away by rain; but very few signs of the effects (in the 
shape of powdered grit) of pluvial disintegration can be discovered, 
while several of the crevices are partly filled, not by decayed grit, but 
by a sandy calcareous clay of the same nature as that which may be 
seen covering considerable areas in Matlock Valley. This clay con- 
tains fragments more or less rounded, and was probably deposited by 
the sea during the last submergence of the land. The Black Rocks 
have acquired their present shape, not by disintegration, but by the 
dispiacement of blocks, leaving walls and pillars, with intervening 
passages, the sides of which are nearly as fresh-looking as when the 
rocks were jeinted, Here the Geologist can likewise see rock-basins 
on the sides of the cliffs, and in positions to which an undermining 
agency only could have had access. But such hollows on the sides 
of rocks are more common on Stanton Moor, afew miles to the north- 
west of Matlock. There also may be seen pillars of rocks like chim- 
neys, consisting of square blocks, apparently piled up, but really the 
remaining fragments of jointed strata. Farther north, on the other 
side of the Derwent, the Millstone-grit rises in pillars, like the 
Cheese-wring of Cornwall. Here they are called ‘Batches of Old 
Cakes.’ That they are very old is evident, for their shape cannot 
be explained by any weathering process now operating on the spot, 
but would seem to point to the lateral action of the sea. Some kinds 
of Millstone-grit are peculiarly adapted to resist weathering. The 
longer they are exposed to the atmosphere, the harder their surfaces 
become; and, with their usual mossy covering, I am convinced they 
may retain certain shapes for a very long period. The Post-office 
and other houses in Cromford were built seventy years ago, and the 
marks of mason’s tools are now as perfect and fresh-looking as when 
the stones were hewn. 
Behind Matlock High Tor there is a deep rent, the bottom and 
ramifications of which have been partly filled with a kind of sand, 
quantities of which have been brought to the surface during lead- 
mining operations. An examination of the sediment in this rent, or 
