210 MIOCENE PERIOD. [Ch. XV. 
a sea-cliff, when the whole country stood at a lower level 
No. 53. 
d 
Section of Inland cliff at Abesse, near Dax. 
a, Sand of the Landes. b, Limestone. e, Clay. 
relatively to the sea. But this can no longer be regarded 
as matter of conjecture. In making excavations recently for 
the foundation of a building at Abesse, a quantity of loose 
sand, which formed the slope d, e, was removed, and a perpen- 
dicular cliff exposed about 50 feet in height. The bottom of 
this cliff consists of limestone, b, which contains shells and 
corals of Miocene species, and is probably a calcareous form of 
the division c (diagram No. 51, p. 207). Immediately below 
this limestone is the clay c (probably d, diagram No. 51, p. 207), 
and above it the usual tertiary sand a of the department 
of the Landes. At the base of the precipice are seen large, 
partially-rounded, masses of rock, evidently detached from 
the stratum b. The face of the limestone is hollowed out 
and weathered into such forms as are seen in the calcareous 
cliffs of the adjoining coast, especially at Biaritz,near Bayonne*. 
It is evident that, when the country was at a somewhat lower 
level, the sea advanced along the surface of the argillaceous 
stratum c, which, by its yielding nature, favoured the waste 
and undermining of the more solid superincumbent limestone 
b. Afterwards, when the country had been elevated, part of 
the sand a fell down, or was drifted by the winds, so as to 
form the talus d, e, which masked the inland cliff until it was 
artificially laid open to view. 
The situation of this cliff is interesting, as marking one of 
the pauses which intervened between the successive movements 
of elevation whereby the marine tertiary strata of this country 
* This spot was pointed out to me by the proprietor of the lands of Abesse in 
1830. 
