527 
EEPORTS OF THE PROCEEDINGS OF GEOLOGICAL 
SOCIETIES. 
Proceedings of the Geological Society of London. — November 3, 1858. — 
The following communications were read : — - 
1. "On some Natural Pits on the Heaths of Dorsetshire." By the Rev. 0. 
Fisher, M.A., F.G.S. 
On AifpudJle Heath and Piddletown Heath, near Dorchester, the surface is 
pitted with numerous circular or oval hollows, like invei'ted cones. They usually 
vary from about 60 to 80 yards in circumference; but one measures 130 yards, 
and another, called ''Culpepper's Dish," is 290 yards round; in the former the 
sloping sides are 23 yards high ; in the latter 47 yards. After observing that 
these pits could not have been formed by the washing away of the underlying 
sand-beds, the author proceeded to show that their formation seemed to be due to 
the subsidence of the material into '• sand pipes" in the sulijacent chalk, owing 
to the percolation of rain-water containing carbonic acid, which dissolved the 
chalk ; and Mr. Fisher referred to the explanation of this process given by Mr. 
Prestwich in a paper formerly read before the Society. 
As this process could have gone on only during a subaerial condition of the 
surface, and must have occupied a very long time, the author remarks that the 
larger pits on the Heaths referred to must have been formed by the sinking of the 
Eocene beds into enormous " sand-pipes" during an extended geological period, and 
that the area they occupy was dry land during all that time, and has been so ever 
since, and must, therefore, have formed islands or headlands in the sea which last 
filled the adjacent valleys, and gave them their present configuration. 
As the formation of these pits was subsequent to tlie outspread of the superficial 
gravel of these Heaths, and previous to the last depression and elevation of the 
land, their date would be, perhaps, near that of the gi'eat mammalian fauna. The 
author also explained his views of the method by which the subsidence of the 
materials gave rise to the peculiar shape of the pits ; and he observed that some- 
what similar conical depressions have been noticed in process of formmtion at the 
present d.ay. 
2. '• Notice of the occurrence of an Earthquake along the Northern Edge of the 
Granite of the Dartmouth District, on September 28, 1858." By G. Wareing 
Ormerod, Esq.,F.G.S. 
The shock was slight, and appears to have been confined to a very narrow 
district, that may be estimated as not exceeding eii;ht miles in width, and running 
along the northerly edge of Dartmoor, alougthe line of junction of the granite and 
the altered carbonaceous rocks. The length of the al-ea affected by the earthquake 
is about 21 miles, from Crediton on the east to the Fox and Hounds Inn, on the 
Tavistock Road, about seven miles from Okehampton. The shock seems to have 
taken a direction from east to west, to have occurrel about eight o'clock in the 
evening, and to have lasted, where most severe, about 15 seconds. 
3. " Notice of certain Veins of Granite in the Carbonaceous Rocks on the North 
and East of Dartmoor." By G. Wareing Ormerod, Esq., F.G.S. 
'i'he following localities are quoted by the author as affording more or less 
distinct evidence of granitic veins traversing the carbonaceous rocks. Near 
Meldon, two miles S.W. of Okehampton ; Cocktrce Moor ; in the George of t!ie 
Teign after leaving Hunts Tor ; the most northerly point of Whyddon Park, and 
the hill-side nearly opposite ; the hill-side above the Logan Stone ; near 
Westerly Tor ; on Sharpy Tor; on the road from Cranbrook Castle to Fingle 
Bridge ; and the ro id down the hill to the west of Cranbrook Farm. 
4. " On the Structure of some of the vSiliceous Nodules of the Chalk." By N. 
T. Wetherell, Esq. Communicated by the President. 
The author first described several specimens of the peculiar banded flints found 
in the chalk and in gravel, and of which he had made a large collection during 
several years. They usually exhibit a central longitudinal axis or narrow stem, 
