432 



THE GEOLOGIST. 



The sliallowing and westing are now increasing with such speed, that they 

 may be measured almost from week to week, and eight feet is probably ail 

 that can be secured at low water spring-tides ; this will be speedily decreased 

 to seven, then to six or five feet, and the trifling swashway, the memorial of 

 the fine channel of 1820, will fill up and be obliterated. 



The silting up of the harbour is almost wholly caused by the inwash from 

 the sand-shoals of the Hook in the last few years. This result will follow in 

 more rapid stages so soon as the sand-banks, which are northing as well as 

 westing, shall have northed to a certain line across the mouth of the harbour. 

 Towards this line the sands have moved in twenty years a quarter of a mile in 

 the three fathom depth. Eor a time the ratio of northing will be possibly a 

 retarding, and not an accelerating one, but in a very few years — perhaps thirty, 

 or less — the bar will have advanced northerly to a line with the sunk vessel. 

 'For a century, and slightly for two centuries, every tide had taken in sand, but 

 a portion was swept out again. JBut during the last fifty years every flood 

 tide has taken in increasing quantities of sand, while no ebb tide ever takes 

 any out. When the bar shall have passed a certain line, the sand will come 

 within the direct influence of the prodigious velocity and power of the water 

 rushing into the confined and narrow entrance, and will move in great quanti- 

 tities ; and although a little may be forced back on the bar at the ebb, a great 

 deposit will be made internally, and one of the finest harbours of Great Britain 

 will be converted into a mere marine marsh. 



To remedy this, Mr. Brannon proposes to restore the entrance to Poole Har- 

 bour to a straight channel of four or five fathoms depth ; or greater if desired. 

 The indispensable work for which would be a breakwater or pier from South 

 Haven, to secure a new channel coincident with the ancient one, or between 

 that and the eighteenth century openings. 



T/ie Geology of Weymouth and the Island of Portland. By Robert Damon. 

 London : E. Stanford, Charing Cross. 1860. 



A writer in the " Athenaeum" a short time since described the requisites of a 

 gaide-book as consisting in having the matter good and reliable, and well 

 arranged, without any superfluity in the shape of tine wiiting or grandiloquent 

 descriptions. It is certainly something to have all the materials so well arranged 

 that you know where to turn at once for anything you want to find ; and so 

 far as reliable matter and this principle of arrangement are concerned, Mr. 

 Damon's " Geology of Weymouth" is a model guide-book, and no tourist or 

 amateur geologist should visit the beautiful neiglibourhood in which he resides 

 without it. 



The illustrations are well selected, and generally weU executed, something 

 to say of a geological book illustrated by wood engravings ; for the generality 

 of these in works on that science are execrably bad, as any one may be satisfied 

 by turning even to some of the works of our best authors. The printer, how- 

 ever, has done nothing towards showing them oft'. 



Mr. Damon seems to have taken great pains to produce a useful and good 

 result, and we hope the sale of his little book may bring the appropriate reward. 



