46 
SEA SAND. 
diameters in some fine Scarbro' sand run from inch to less 
than inch. But different samples of sand are of obviously 
different fineness. Thus from Thornwick Ba) r , near Flambro’, 
comes a much coarser sample of angular flint sand, the 
particles being about as coarse as fine shot. 
Another plan was to scatter a known weight or volume of 
sand evenly over a sheet of paper, ruled in squares, and by 
counting the numbers of grains on a few squares to estimate 
the total number. 
In any small portion of the sand, as it lies on the shore, the 
grains are generally of about the same size—that is, fine mud 
and coarse gravel are not as a rule mixed with it. 
When such a natural sample of sea sand is thrown into 
water, the particles sink at not very different rates. This is 
because the sand has already been water sorted. The finer 
particles have been carried away altogether. The gravel has 
settled previously, and the sand falling later has partly filled 
the interstices of the gravel and also formed a layer on top of 
it. The swift currents round a cape leave only large blocks of 
stone ; in exposed bays like Cornelian Bay, gravel is left; in 
Thornwick Bay near the Flamboro’ headland, a coarse sand ; 
in the sheltered Scarboro’ South Bay, a fine sand ; but even 
there the finer mud has been carried away. 
At high Spring tides when the waves reach the clay banks? 
the sea is muddy for a hundred yards or so from the Scarboro' 
cliff banks, and some of this mud is left in the rock pools from 
which it is afterwards swept away by succeeding tides. 
There are other ways in which sand may get sorted into 
sizes. If a dish of dry sand and gravel is shaken, the sand 
will shake down through the interstices of the gravel. So 
although gravel settles first in water, the sand may afterwards 
find its way down among the interstices of the gravel. Digging 
into the Scarboro’ sand below the Holbeck Gardens, I have 
found first a layer of fine sand and then underneath this mixed 
sand and gravel. 
At the Gravel Pits beyond Fulford, when a various mixture 
of sand and gravel is tipped out from the truck, the larger 
stones collect at the bottom of the heap. This is because the 
irregularities of the heap are rough relatively to sand grains 
