RISTOL NATURALISTS SOCIETY. 
EXCURSION MEETING, Aug. 15th. 
i^rowU/ie " Bristol Daily Fost'' of August 19th, 1864. 
The third and concluding excursion for this season took 
place on Monday last, Aug. 15. The locale chosen on this 
occasion was the well-known Aust cliff, specially interesting 
to geologists, from its containing a little bed with peculiar 
fragnaents of fossil bones— which has also been discovered 
cropping out at Axmouth, in Devonshire, and Westbury, 
places fully sixty miles distant. 
On this occasion the number was more limited than usual, 
only twenty-four members being present, and no ladies. 
.They left by the 12.30 train for the New Passage, and after 
a slight lunch at the Hotel, walked along the shore in the 
direction of the cliff. On account of the drought, scarcely 
^ny plants of interest were found, and the consequent hard- 
ness of the ground prevented the perfect beetles peculiar to 
such localities from making their way to the surface. The 
scientific interest of the walk therefore was solely geological. 
At the distance of a mile, the clearness of the air enabled 
the various strata to be readily discerned, the cliff presenting 
the appearance of a coloured geological sectional map. On 
arriving at Aust, the President, Mr, W. Sanders, F.R.S., 
F.G.S., gave a description of the strata thus admirably dis- 
played. These comprise the highest beds of the New Red 
Sandstone, and the lowest of the Lias formation. The red 
marls at the base support about 10 feet of pale greenish 
marls, including a six-inch bed of marly sandstone. Resting 
on these marls the Lias commences with a thin bed contain- 
ing remains of fish. The next 12 feet consist chiefly of 
black laminated shales, and they include three thin beds 
yielding remains of fish, insects, and various bivalve molluscs. 
The following 25 feet are composed of alternations of thick 
marly clays, and thin beds of limestone — the highest of 
which is known as Gotham marble. This portion of the Lias 
formation has received various appellations : the older 
Geologists called it the Lower Lias Clays ; next, the Avicula 
contorta beds, that shell being limited to these strata; sub- 
sequently it has received the name of Rhaetic beds, on ac- 
count of its geological aflanity with strata which occur in 
great force near the Rhaetian Alps. At the distance of half- 
a-mile further along the' shore, the red marls presented a 
thickness of nearly 100 feet, at about 60 feet below the upper 
limit of which abundance of fibrous gypsum (sulphate of 
lime) occurs in horizontal layers, intersected by nearly ver- 
tical veins and threads : strontian, too, occasionally occurs 
in this stratum. At this part of the cliff it was observed that 
the fish bed resting on the pale green marls, which at the 
southern end of the cliff was seen to be very thin, had gradu- 
ally expanded to a thickness of eight or ten inches, and con- 
sisted of a conglomerate mass of rounded portions of the 
subjacent marly sandstone, coprolitic nodules, detached 
vertebral and other bones of the Piesiosaurus, parts of fish — 
especially teeth— and some shells. It is this bed which is 
famous in all text-books on Geology under the name of the 
Aust Bone-bed. 
In the course of the walk, three examples of dislocation of 
the strata were seen, the nature of the faults was explained, 
and they were shown to possess all the characteristics of 
normal faults as they occur in coal-mining. Many of the 
party worked hard with hammers and chisels, and were for- 
tunate in obtaining good illustrations of the Bone-bed, and 
other specimens. A portion of a vertebra and other bones 
of a Piesiosaurus, a spine-bone of a fish, Nemacanthus; 
teeth of the Ceratodus, Saurichthys, and Hybodus, were 
found, together with various fossil shells, as Pecten 
valoniensis, Cardium rhaeticum, Modiola minima, Anatiua, 
