291 



indicate differences in geological age. These distinctions, as stated under Sec- 

 tion A, are : — Pleistocene, mottled sands and clays ; Recent, red clays and small 

 gravel, passing up to a capping of concretionary limestone and marls, which 

 latter are present-day deposits. 



These newer beds are particularly well exposed in the amphitheatre of Hal- 

 lett's Cove, carved into successive spurs by the rain causing little rivulets to wash 

 out channels down the face. The mottled sands and clays (Pleistocene), which 

 are slightly more indurated than the overlying red clays, show steeper faces than 

 the latter and are sometimes cavernous. The section is a very striking example 

 of the eroding effects of rain on soft rocks. The entire Cove, as an excavated 

 area, has been formed by this simple agency. The surface at the top of the 

 amphitheatre is higher than the ground at the back, which has a gentle slope to 

 the east, so that no water finds its way into this amphitheatre except by the 

 direct fall of rain within the area. The waste on the face of the cliffs, by this 

 rain wash, is so rapid that no vegetation can establish a footing on these bare 

 slopes. The retreat of the cliffs within the last 35 years is most marked (Howchin, 

 W., 1918a, p. 69, figs. 51, 52), and as the ground at the back slopes away from 

 the edge of the cliffs, the height of the cliffs will gradually diminish. 



Section of Beds within the Amphitheatre at Hallett's Cove. 



Recent: — Feet. 



Light sandy soil . . . . . . . . . . . . . . . . 2 



Concretionary travertine and marl (6 feet to 15 feet) . . . . 9 



Red and greenish clays, sometimes gravelly . . . . . . . . 20 



Pleistocene: — 

 Mottled red and grey argillaceous sands and clays . . . . . . 40 



Lower Pliocene (Kalimnan) : — 

 Calcareous sands and grits (fossihferous), stony at base, including 



derived erratics from the underlying till . . . . . . . . 3 



Age Doubtful: — 

 White sand, underlying the fossihferous Pliocene but is quite dis- 

 tinct from it. Does not carry stones and is very fine and 

 regular in the grain. Unfossiliferous. Is not present on the 

 Black Point shelf ; is slightly exposed on the northern side 

 of the Cove and thickens in the exposures in washouts on the 

 southern side . . . . . . . . . . . . . . 15-60 



Permo-Carboniferous: — 

 Glacial clays, sands, and grits, ranging from low-u-ater level to 

 80 feet and 100 feet above sea level. Near the head of the 

 Cove the till forms a finely laminated clay of a deep-red colour, 

 which on the surface weathers into flakes of about an inch in 

 diameter ; in other positions the till takes the form of a greyish 

 clay. It carries erratics of all sizes up to 8 feet in diameter. 

 Near the coast the till is a sandy and gritty bed with glaciated 

 boulders resembling the indurated sandy till of the Mount 

 Compass district . . . . . . . . . . . . . . 90 



Cambrian : — 

 Purple slates and quartzites form the northern and southern limits 

 of the over-deepened glacial valley. 



The sea-cliffs to the southward of Hallett's Cove exhibit very markedly 

 the features of a double cliff. The Cambrian purple slates that form the lower 



