NATURE'S SAND-BLAST. 39 



Nature's sand-blast is indeed a powerful engine, for it 

 has pitted and polished the upper surface of every rock and 

 stone in the desert, besides so smoothing and rounding many 

 a boulder that it looks as if it had been rolled about in the sea. 



In other parts of the world a glance at the rocks on the 

 coast is often enough to tell one the prevailing direction 

 of the wind, so much have they suffered on that side. At 

 Heard Island the sand-blast has cut the rocks into tree-like 

 shapes; in the Bermudas (Fig. n) it has given them an arti- 

 ficial appearance as of being cut and dressed by a mason's 

 chisel ; in a pass to the south of the Great Salt Lake the 

 hills are worn away and the rocks polished by the ceaseless 

 scouring of the sand driven against them from the west ; and 

 in an island in Lake Kara-Kul, not only has the surface of 

 the hard sandstone suffered considerably, but some of the 

 rocks have been drilled through by the sand-laden wind 

 from the north. 



Then again, stones have been brought from Lyell's Bay, 

 near Wellington, New Zealand, many of which the un- 

 initiated would certainly imagine to have been shaped by 

 human hands, so strongly do they resemble the knives, arrow- 

 heads,spear-heads, &c., of what is called the Stone Age. All 

 have sharp-cutting edges, and their facets seem to have been 

 chiselled with careful attention to symmetry. Yet the only 

 chisel used upon them has been the sand of the bay, and 

 the hands which guided it were the two winds there domi- 

 nant, which have urged the sand against opposite sides of 

 the stone in turn, each grain of sand chipping away its 

 infinitesimal bit of stone, and in the end sculpturing these 

 singular forms. 



