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served in the deeper waters off-shore. In the Covey Hill 
distiict shells have been found only as high as 260 feet 
(72:2 m.). Artificial excavations on both sides of the 
road, a half mile south of Hemmingford village show 
a large number of Saxicava arctica in a loosely packed depo- 
sit of very coaise gravel. The presence of complete 
shells with valves shut together, standing in attitudes 
of growth between heavy cobblestones, shows a surprising 
capacity in Saxicava to withstand heavy surf. It is per- 
haps strange that the shells have not been dissolved 
away, where so much open space is present. The upper 
three or four feet of the deposit, however, are barren; 
and the abundance of shells in the underlying strata may 
be due to the presence until very recently of the water 
table at that height. The upper, barren zone, shows 
considerable oxidation of iron, while the fossil-bearing 
beds are of blue colour. 
A better guide to the upper marine limit consists in 
the wave-built beaches, which in this district are exception- 
ally fine. As one approaches Covey Hill village by road 
from the east, well-built ridges of water-worn sandstone 
shingle make their appearance. The first of these are 
near the 300-foot (91-4 m.) mark. From this level up to 525 
feet (160 m.) there is a rapid succession of them. A very 
conspicuous group of them crosses the road near Covey 
Hill Methodist church, half a mile east of the post office. 
One upon which the church itself is built is 507 feet 
(154-5 m.). Below this one, at a barn, are two strong 
ridges of sandstone slabs, at 500 and 496 feet (152-4 and 
I51-2m.). Although the slabs of rock are poorly rounded, 
their imbricated structure shows plainly that they have been 
slapped up into their present positions by wave action. 
The crests of the beaches are very uniform, and their 
front and back slopes very graceful. About 250 yards 
(228-6 m.) from the church farther up the road is the 
highest beach of all, at 524 feet (159-7 m.). Winiemis 
distinct, although not as conspicuous as the lower beaches, 
because it has very little back slope. On the road which 
runs northward from the post office, a similar series of 
beaches is crossed, which correspond closely in altitude 
to those just mentioned. In descending order these are 
524, 517, 506, 500, and 455 feet (159-4, 157-6, 1542, 152-4, 
and 138-7 _m.). The beach form and the wave-worn shape 
