ON THE SMALLEST DELTA 351 



rain-water, percolating through the sandy chffs, 

 reaches a layer of clay, or rather hardened mud, 

 which here lies above the level of the beach. The 

 streamlet becomes reduced to a thread-like trickle, 

 having only the thickness of a finger, but it con- 

 tinues to flow for days. When it emerges at a 

 moderate gradient it deposits an alluvial fan, but 

 when it overflows the bed of clay and descends 

 very steeply it deposits its burden of sand in a 

 different manner. The stream is subject to fluctua- 

 tions both of velocity and direction. Diminution 

 of speed is immediately followed by the deposition 

 of a little tongue of sand at the extremity of the 

 stream, and the thread of water is instantly 

 deflected, darting out in another direction, where 

 another tongue of sand is quickly formed. The 

 process goes on very quickly, the thread of water 

 darting this way and that like a living thing, the 

 tongues of sand being built up with such quick- 

 ness that in quite a short space of time a very 

 pretty frond-like structure is produced. The whole 

 process, indeed, goes on so rapidly that it would 

 make a good cinematograph, even if the instrument 

 were worked, and the picture reproduced, so as 

 to show the real rate of operation. 



The size and shape of the tongues of sand are 

 of interest and significance. The surface of the 



