SEA SAND. 
53 
been remarkable for the great variety of its pebbles —notably 
the occasional cornelians and agates. 
An attempt to arrange these pebbles as a geological collection 
at once shows that there are many dozens of different sorts— 
the difficulty is perhaps to find any two that exactly match 
and yet they can be arranged in about half-a-dozen main 
groups. The cup of poison which Medea spilt must have 
contained some acid, for it made the marble pavement hiss 
and bubble ; and the Geologist’s test for marble or any other 
sort of limestone is to place a drop of hydrochloric acid on the 
stone, and notice whether any bubbling occurs. 1 his test 
allows us to quickly pick out the limestone pebbles from among 
the gravel, and some sorting done in this way indicates that 
about i pebble in every 6 is a limestone of some sort. Other 
large groups that can be picked out are the sandstones, the 
quartzites, some dark stones possibly basalt, and a variety of 
stones of mottled texture which appear to be either granite or 
other stones of igneous origin. 
Geologists say that some of these granites are unlike any 
British rocks, but resemble certain Scandinavian granites. If 
so, their presence here can only be explained by supposing 
that they have been brought upon ice at a time when our 
islands enjoyed a climate like that of Greenland to-day. 
The Scarboro’ cliffs are all capped with clay, glacial clay 
full of pebbles. The seabanks are undrained, and the clay is 
very wet in winter, so that it is in continual slow glacierlike 
movement—a movement which threatens to carry away the 
promenade down towards the sea. On reaching the shore the 
waves either wash away the clay or cover it with sand. 
On treating a sample of this clay so as to wash away the 
finer portions, a considerable quantity of sand and grit is left. 
Here is one source of sand other than the rock of the cliffs. 
Larger stones emerge from the clay at times, among which 
scratched and polished boulders of the mountain limestone are 
not infrequent. Isolated blocks weighing some hundredweights 
are frequently seen littered across the rocky reefs along the 
coast. The largest I know, a rock called the Dutchman, 
which must weigh many tons, stands amidst the sand at 
Newbiggin-by-the-Sea, 
