206 ON THE EROSION OF THE SHORES OF THE SEVERN ESTUARY. 
is some on the tidal banks of the Avon near the mouth of the 
Trym, but this is largely due to the wash of the steamers ascending 
the river to Bristol. 
Aust Cliff consists of the Red and Grey marls of the Keuper, 
overlain by the shales and limestone bands of the Rhaetic and Lower 
Lias. Throughout the greater part of its length the base of the 
eliff is only reached by the water at highest spring-tides, and the 
main erosion is subaerial, the base of the cliff being occupied by an 
angular talus and never overhanging. Aust Cliff, however, differs 
from the opposite Sedbury Cliff in being in the main free from 
\’egetation. Its recession is principally due to the separation of 
masses of the marl along vertical joints, or sometimes along planes 
of weakness due to the numerous gypsum veins. A portion of the 
northern part of the cliff differs from the remainder in being reached 
by the Severn at high tide, and undercut chiefly owing to the 
detachment of masses of gypsum. In the neighbourhood of each of 
the three faults which occur near the southern end of the cliff the 
strata have been remarkably indurated, and give rise to small 
promontories which stand out as much as 30 feet from the main 
face of the cliff. The greatest amount of erosion has taken place 
near the southern end in spite of the protection afforded by a 
landing stage (disused since the opening of the Severn Tunnel). 
The last thirty feet of this landing stage have been broken up by 
the Severn, and about half the garden of a neighbouring cottage 
has disappeared. 
4. — From. Aust Cliff to the Arlingham Peninsula. 
From Aust Cliff to near the mouth of the Little Avon the coast 
is formed of alluvium. Near Sharpness Point the Old Red Sand- 
stone comes down to the coast and stretches as far as Tite’s Point, 
where, however, the river is actually bounded by low cliffs of 
alluvium and re-arranged material, the Old Red and associated rocks 
being worn down to a mud-covered platform quite inaccessible under 
ordinary conditions. Alluvium again forms the coast from Tite’s 
Point as far as Frampton-on-Severn. Hitherto the course of the 
Severn has been practically in a due south-westerly direction, but at 
this point it commences to wind very much, and at each bend there 
is deposition at the salient and erosion at the re-entrant angle. 
At Fretherne, on the southern shore of the Arlingham peninsula, the 
Lower Lias consisting of shale with subordinate limestone bands 
crops out upon the coast for a distance of about a mile. Here 
erosion has been very rapid of recent years. According to a man 
who gets his living by fishing and fowling on the river the coast in 
the neighbourhood of Hock Crib, but especially to the south of that 
point, has lost upwards of fifty yards in the last 30 years. This is 
probably an exaggeration, but there can be no doubt that the loss 
has been very considerable. A little further to the south at Frampton 
the alluvial area has been much added to. At Smith’s Wood (Butcher’s 
Cliff of the old geological survey map) the Lias is succeeded by an 
area of alluvium which extends all round the end of the peninsula. 
