Corresponde7ice — Colonel Greenwood. 143 



accepted the cautions of the author as to hasty deductions from the dip of strata at 

 the surface. 



Mr. Etheridge considered that the Lower Lias was of greater thickness at Bur- 

 ford than supposed by the author. 



The Author, in reply, stated that he did not dispute the fact of the Palseozoic 

 rocks being much disturbed and crumpled, nor did he deny that there may have 

 been some disturbance of the upper beds. What he wished to point out was that 

 the disregarding of the fact that strata thickened in certain directions might be 

 and had been a fruitful source of error. 



coI^I^ESI='O^^X3:B3^c:E]. 



OEIGIN OF THE FLEET. 

 Sir, — On this subject, in your February number, my friend Mr. 

 Kinahan follows Herschel, Lyell, Bristow, and Whitaker in at- 

 tributing the heaping of the Chesil bank to " tidal currents." 



In your November number for 1869 you did me the honour to 

 publish my opinion, at some length, against these high authorities. 

 May I beg space now for a short repetition ? 



The Chesil bank is 42 feet above high- water. Shingle does not 

 travel on the high- water surface of a " tidal current," but if it did, 

 how could this current land the shingle 42 feet higher than its own 

 surface ? The wind causes the travelling of beach, and I gave this 

 sing-song rule for it — 



" As the wind blows, the wave flows ; 

 As the wave flows, the beach goes." 



It is not a "tidal current," it is the prevalent south-west wind 

 which throws beaches across the mouths of so many of our streams 

 on the south coast, and which drives them eastward as they enter 

 the sea, and among them all the side streams which fall into and 

 from the Fleet. 



The reason of the enormous heaping of the Chesil bank is that 

 the travelling of the beach down the wind is interfered with by the 

 peninsula of Portland, which runs out to sea at right angles to the 

 bank, and acts as a gigantic " natural groin." 



It is not only that shingle is now constantly torn down and again 

 landed on the top of the Chesil bank, but a vessel has been heaved 

 bodily over it and into the Fleet. Does Mr. Kinahan think that 

 the vessel floated calmly over the bank on his "tidal current run- 

 ning parallel, or nearly so, to the coast line," or that it was lifted 

 over by the impact given to the wave by a south-west storm ? 



I wisb that I could persuade my friend Mr. Kinahan to read 

 Chapter viii. of "Eain and Elvers" on the "Travelling of Sea-beach," 

 where all this is discussed at length. 

 Bkookwood Park, Alresford, George GREENWOOD, Colonel. 



bth February, 1874. 



WELL-SINKING IN THE LINCOLNSHIEE FEN-DISTRICT. 



Sir, — I should be very much obliged to any of your readers who 

 could give me information, or references to books where I can 

 obtain it, on the following point : — 



At Lincoln the fen, that extends along the right bank of the 



