422 PROF. J. LOGAN LOBLEY, F.G.S., F.R.G.S., ON 
As is well known, the Landes is an extensive plain very little 
above the sea-level, spreading inland for a distance of 100 
miles, and extending along the Bay of Biscay from the 
Adour to the Gironde, a distance of about 150 miles. ‘The 
coast of Spain on the other hand is mountainous, the 
western extension of the Pyrenees, the Cantabrian mountains, 
fringing the shore-line, with their spurs forming head lands. 
Corresponding, too, with the physical features of the two 
coasts 1s, as might be expected, their geological structure. 
The flat French coast area is formed of Quaternary accumu- 
lations overlying Miocene and Eocene strata, while the 
rocky, hilly, and mountainous Spanish coast lands are 
composed of strata of Secondary and Paleozoic Age. 
Of the rivers flowing into the Gulf of Gascony, or south- 
east angle of the Bay of Biscay, the principal is the River 
Adour, which, although called by Dr. Blanford a comparatively 
trivial str eam, 1s better, I think, described by Professor Hull 
as “a fine river.” It hasa breadth at the city of Bayonne 
of 800 feet, and from its source in the Pyrenees to its mouth 
measures at least 200 miles, and has several important 
tributaries, as the Nive, which joinsit at Bayonne, the Oloron, 
the Gave de Pau, and on the north, the Midouze, which give 
the Adour a large drainage area extending for fully 120 miles 
along the northern side of the Pyrenees. About fifteen miles to 
the south of the mouth of the Adour, the River Nevelle 
flows into the sea at St. Jean de Luz. This at present is an 
unimportant river, but alittle farther to the south and joining 
the sea at the very angle of the Bay of Biscay there is a 
river that deserves more attention than it generally receives. 
This is the River Bidassoa, the boundary river between 
France and Spain, and differs from the Adour and the 
Nevelle in draining the south side of the western part of the 
Pyrenees. It is even now a considerable stream, and the 
alluvial flats seen as Fuentarabia, at its mouth, is approached 
shows that in quite late Quaternary times it was a much 
greater river. ‘These three rivers, the Adour, the Nevelle, 
and the Bidassoa, now pour their waters into the sea at the 
head of the Fosse de Cap Breton. 
We may now inquire whether, under the conditions that 
must have obtained with an elevation of the contiguous 
lands to 9,000 feet above their present levels, the output of 
ice, and afterwards of water, together with the action of the 
sea at the bight of the Bay of Biscay, would not be ot 
sufficient erosive power to produce the Fosse de Cap Breton, 
