714 Miniature Physical Geology. [December, 
advanced, planing off the upper portion, and forming tiny 
cliffs of delta material, but leaving the deeper parts of the 
deposit intadt. 
XL Miniature Tides. 
When a little stream flows into the sea one may watch, as 
the waves roll in, estuary tides in miniature. The point 
with respedl to these to which I directed my attention was, 
whether the tide as it came up “made” first along the shore 
or in mid-stream. But though it always did one or the 
other, and seemed always to do the same in the same 
stream, I am unable to say which is the more general. Nor 
can I say what causes bring about the one result or the 
other. I fancy that where the stream has shelving banks, 
and runs in a concentrated current, the tide makes along- 
shore ; but that where the stream is wide, and widens out 
still more where it enters the sea, the tide makes up the 
main channel. This view, however, I cannot substantiate 
by observation. 
XII. Miniature Lake Terraces. 
On the sands near St. Catherine’s Point, in the Isle of 
Wight, and again not far from Dolgelly, in North Wales, I 
have noticed the formation of miniature lake terraces. The 
only point worthy of notice with regard to these is, that 
they never extended individually more than half a foot or a 
little more in length, and that the terraces were at various 
heights. It seemed as if the formation of terraces was more 
or less continuous if the whole lake was considered, but in- 
termittent if particular portions of the lake were regarded. 
This seems to me to help us to understand how a series of 
terraces, such as those which are found on the shores of 
Lake Superior, may be made by a continuous lowering of the 
waters of the lakes. 
XIII. Sand Ripples. 
On any extensive stretch of sands the way in which the 
sand-ripples are formed by the wind may be watched. It is 
curious to notice that a series of ridges is almost invariably 
formed. These ridges present a sloping face to windward, 
and an abrupt face to leeward. When it is blowing hard a 
quite remarkable sand haze may be seen quivering over the 
surface, as lighter sand grains are caught up by the wind ; 
