ILLUSTRATIONS 27 



Plate 

 No. Page 



74. Deposit of cliff-sand, containing an admixture of fine par- 



ticles, left after subsidence of water, showing transverse 

 ridges ; at Bournemouth ..... 347 



75. Deposit of cliff-sand, containing an admixture of fine par- 



ticles, showing transverse ridges formed by subsidence 



of water ; at Bournemouth .... 350 



76. Deposit of muddy sand carried down the cliff by water, 



showing no transverse ridges ; at Bournemouth . 353 



77. Rippled cirrus cloud, seen from Branksome Chine, near 



Bournemouth ...... 357 



78. A " mackerel sky," seen from Branksome Chine, near Bourne- 



mouth, August 5, 1900, looking west . , . 361 



79. Wave-clouds, or "mackerel sky," seen from Branksome 



Chine, near Bournemouth, August 5, 1900, looking 

 south ....... 365 



80. Negative of the photograph of wave-clouds, in which the 



blue sky appears light and the clouds dark, showing 

 that it is the blue sky and not the cloud which more 

 closely resembles the ripple-mark of sand . . 368 



Fig. 

 No. 



FIGURES IN THE TEXT. 



Sir G. H. Darwin's diagram of currents flowing over ripple 

 mark ...... 



2. Profile of sand-dune with crest reversed by contrary wind 



3. Sand-dune with undulating crest, showing development of 



peaks and saddles ..... 



4. Profile of twenty-nine snow-waves near Winnipeg 



5. Profile of twenty-four aeolian sand-waves, near Helwan 



Egypt 



6. Barchans of snow and sand, from photographs 



7. A patch of rippled snow, plan .... 



8. Conversion of above to a barchan, early stage 



9. The same at a later stage .... 



10. Erosion waves in compact snow, with grooves showing 

 stratification, wind from the right hand 



39 

 62 



65 

 107 



109 

 114 

 129 

 129 

 130 



134 



