1 88 1.] Miniature Physical Geology. 715 
and after bathing I have noticed a stinging about the ankles 
produced by the cannonade of little grains, the sand mean- 
while being heaped up on the windward side of my feet. 
During a gale, and still more during continuous winds such 
as the ‘ south-easters ’ of the Cape, this sand cannonade 
must have some effeCt in eroding even hard rocks. That 
this actually is the case may be very clearly seen on the 
Cape Town side of Camps Bay, where the granite rocks 
have a very peculiar surface, eaten into deepish conical holes, 
which I feel sure have been produced in this way. 
The sand-ridges above mentioned are constantly advancing 
in the direction in which the wind is blowing, hut they are 
stopped by the smallest stream. I was struck some years 
ago, when I was in Cornwall, at the faCt that quite a small 
stream stopped the advance of the sand dunes near Hayle, 
so that this stream formed a boundary between green grass 
flats and a wilderness of sand. This reminds one of Prof. 
Jukes’s remark ; — “Egypt would probably have been long ago 
obliterated by drift sand, if it had not been for the Nile, and 
the strip of vegetation that accompanies and defends it.” 
Near Ouchy, on the Lake of Geneva, I had a good oppor- 
tunity of seeing the formation of sand-ripples under water. 
My note on the subject runs thus : — “ As each wave passed 
the little ridges advanced, the sand being raised in a small 
cloud up the sloping side of one ridge, over the intervening 
gap (falling down the steeper side), and being deposited on 
the sloping side of the next ridge. Thus the whole set of 
ridges advanced gradually.” 
XIV. Miniature Earth Pillars. 
Those who have visited Switzerland or the Tyrol probably 
know well the nature of earth pillars. Those who have not 
perhaps know something about them at second-hand, through 
the pages of their Lyell. Such earth pillars may be seen in 
miniature almost anywhere. On the sea-shore a broken 
shell protecting the sand beneath it from the aCtion of rain 
becomes raised on a little pedicel or miniature earth pillar. 
The sloping banks of the very ditches offer examples some- 
times 2 or 3 inches high : these are, however, so well known 
as to call for no comment here. I may only mention that 
the finest miniature examples I have seen were on theTijuca 
road, not many miles from Rio. They were in a decom- 
posed granite slope, were capped by bits of less decomposed 
rock, and were about 9 or 10 inches in height. 
