180 SITE OF PLYMOUTH ONCE A PENINSULA. 
material, whilst in the back ground also, the river 
gains every facility for alluvial deposition. 
When the lowness of the slate tract which passes 
to a junction with the limerock of the coast from 
the higher hills of the South Hams, and which con- 
stitutes the chief site of Plymouth is considered, it 
must naturally be inferred, that not only was that 
spot submitted to submersion at those periods of 
sudden ingress of the ocean which I have before 
spoken of,—the sea occupying the bays and creeks 
of the slate hills at our back,—but that even in very 
modern times anterior to the building of the town, 
and before the filling up of estuaries and the general 
retreat of the northern seas had sufficient influence 
to keep the tide to somewhere near its present bound- 
ary, it has been gradually retiring from this tract, 
and at the first building of any settlement had re- 
treated towards the space between Plymouth and 
Stonehouse, and which as above said, constituted 
for some time and no longer than a century ago (?) a 
creek for anchorage of small vessels ; according to 
which supposition, the lime hills or ridge between 
the sea and the town would have been insulated, 
as also perhaps that range fronting Stonehouse and 
Devonport, and the sea moreover occupying as just 
said the deep and graceful sinuosities and defiles 
between the slate hills, would stretch up behind the 
land directly north of Plymouth at Lipson on the 
one hand and at Stonehouse Mills on the other, 
and these two creeks approximating towards the 
rather low tract (Mutley Plain) intervening between 
those points, would occasion a near insulation of a 
small series of elevations whose actual separation 
from the surrounding districts by vallies nearly on 
a level with the estuaries, and by portions of water 
still existent, remains also particularly apparent in 
our own day. 
