Abstracts of Memoirs. 349 
lesser hills of South-eastern Devonshire. In all other respects the 
physical characters of the district were as at present.—2nd. This was 
followed by a subsidence, the entire area ultimately becoming at 
least 300 feet lower than now. During this depression, marine 
gravels—not entirely of immediate, but never of very remote deri- 
vation—accumulated in the valleys until they were entirely obliter- 
ated; the summits of the hills were also covered, and similar 
materials were lodged in such fissures and crevices as traversed the 
rocks. Dartmoor existed as an archipelago, and was probably in- 
habited by the Dwarf-birch and Willows suitable to the Arctic or 
Sub-arctice climate which then prevailed.—3rd. A slow and uniform 
upheaval then brought up the entire district untilit was no more than 
about 200 feet lower than at present. During this movement very 
much of the gravels previously deposited were stripped off.—4th. 
At this point the upward movement was intermitted, and no further 
change of relative level occurred for a very prolonged period. 
During this interval the breakers, by grinding down the outcrops 
of hard,inclined beds of limestone, produced the extensive horizontal 
platforms of the Torbay district.—5th. To this succeeded a resump- 
tion of the slow and uniform elevatory movement. The limestone- 
terraces first emerged into dry land; the gravels were wholly or 
partially swept out of the valleys, but possibly, and at least in some 
cases probably, still more slowly than the district rose; small patches 
of it were left, or perhaps re-deposited, here and there, on the hill- 
slopes as they rose above the sea-level, as, for example, on Windmill 
and Parkham Hills at Brixham, about 50 feet below the terraces 
just mentioned. Bovey Plain and the Brixham Cavern, each 50 feet 
lower still, at length became sub-aérial, and gradually the total ele- 
vation of the land produced by this second upheaval amounted to 
about 125 feet. Betula nana and the Salices probably took posses- 
sion of the occasionally flooded Bovey Plain as soon as it was ready 
for their reception, which could not have been earlier than towards 
the close of this period; but the land was not yet high enough for 
the fluviatile introduction of the bone-bed of the cavern.—6th. Again 
the upward movement was suspended for a long time, and, during 
the pause, the breakers planed down the terrace represented by the 
Roundham-head Level.—7th. This achieved, the district once more 
began to rise, and when the Brixham Cavern had reached an eleva- 
tion of not less than 40 feet above the sea, its bone-bed, with the 
multifarious articles found in it in 1858, might have been carried 
in; but, though it is apparently impossible to assign this event to an 
earlier period, there seems nothing to prevent its having belonged 
to a considerably later one. Whenever it took place, however, the 
bottoms of the adjacent valleys—whether of undisturbed gravel or 
of limestone rock—were not below the cavern-level; and at this 
height they must have remained during the very prolonged period 
represented by the deposit in question. This upheaval increased 
the elevation of the land by about 45 feet, or, in other words 
brought it up to within 30 feet of its present height.—8th. Once 
more the emergence was suspended, and in the pause were produced 
