15 
which, has also occurred preceded and did not follow it. An abstract of 
the paper was printed in the proceedings for 1870. My purpose now is to 
fortify the arguments then adduced by others derived from ; another part 
of the same district. The observations then recorded were made in the 
neighbourhood of Falmouth on the south coast of Cornwall. Those I 
have to bring forward to-night were made in Bideford or Barnstaple Bay 
during an excursion of a day or two in the month of July, 1869. 
All the headlands along this coast consist of slaty and sandy strata 
dipping to the S. by W. at a high angle, often 75°. They compose the 
debatable ground between the Carboniferous and Devonian systems as 
conformably they dip and form the northern side of the great S.W. 
Synclinal. The mouth of the river nearly overlies the point which would 
be called the junction of the two systems. They however most likely 
shade into one another as gradually as do the corresponding beds in the 
Avon section at Bristol. After passing under the peat and culm beds of 
Mid-Devon they re-appear in the south and form the immense thickness of 
crumbling slate of which the County of Cornwall in great part consists 
and in which lie the massive limestones of Plymouth and Torbay, The 
middle of these counties therefore is a trough of Carboniferous rocks lying 
W. by N. and E. by S. The western part of this trough is drained by the 
rivers Taw and Torridge emptying themselves by Barnstaple and Bideford 
into the Bay of the same name. All the bays round the coast are 
encumbered with sand produced by the wearing action of the waves upon 
the projecting headlands and thrown up by the prevalence of westerly 
winds. Near Braunton it has collected in mass sufficient to form Burrows 
or Sand-dunes covering several square miles of ground and forming one of 
the most barren and desolate spots that can be found in England. Here 
and there grows a tuft of the Sand-reed or the Sandwort but these 
excepted no living plant is seen and the population seems limited to a few 
rabbits that must find a maintenance with difficulty and not unfrequently 
leave their bones to whiten on the surface mingled with those of sheep 
which having wandered too far into the desert could not return, and of 
birds, perhaps wounded or sick, that lay down here and died. 
This blown sand covers the whole district between Saunton Down and 
the Estuary, but on the other side of the river the country has a very 
different appearance. Though composed of sand its surface is level and 
covered with a coarse maritime vegetation just sufficient to support the 
cattle and geese of the neighbouring cottagers. It is protected from the 
sea by the pebble ridge, a long high beach of rounded boulders 
