GEOLOGICAL DESICERATA* 



251 



In many localities the chalk and chalk-marl present^ especially alotl^ 

 the foot of the chalk-downs, and at the base of dhalk-cliffs, a natural 

 detritus, which, by careful manipulation, is found to yield rich harvests 

 of microzoa. ]\Iy friend, Mr. Harris, F.G.S., of Charing, Kentj hsts fof 

 some years availed himself of the abundant store of foraminiferS and 

 other minute fossils which he finds in the argillaceous chalk-detritus,'^ 

 or, more properly speaking, decomposed chalk-marl of his neighbour- 

 hood ; and the plan that he has lately pursued in obtaining these pretty 

 objects free from their tenacious matrix, is as follows :— The detritus,'' 

 liaving been dug up, is exposed for a time to the air, and then portions 

 are placed for some days in a trough of water until they become soft ; 

 small quantities are next put, with a large proportion of water, into a 

 small harvest-barrel, which is then carefully closed with a bung-cork, and 

 the outside of which is armed with bucket-flanges, as in the case of an 

 ordinary overshot mill-Avheel. Making use, as a motive power, of a 

 little stream running through his meadow, and suspending the barrel 

 on pivots against a miniature weir, Mr. Harris secures the constant 

 revolution of the barrel, and consequently a continual churning process, 

 which reduces the detritus in the barrel to a creamy consistence. The 

 contents of the barrel are then poured into a long conical canvas bag, 

 which is set in the stream, and by the natural flow of the water and a 

 continued dipping, by aid of its handle, gradually loses the finer chalky 

 material and retains a coarse sediment. Care is taken to keep the 

 mouth of the bag about the surface of the water; otherwise some of the 

 more valuable sediment would bo washed out by the regurgitating 

 current and lost. The residue is taken into the house, dried, sifted, 

 and picked. 



Sometimes it is found advisable to subject some portions of the 

 sittings, or of the picked specimens, to a further churning in a small 

 bottle of water affixed to the outside of the water- w^heel. 



GEOLOGICAL DESIDEllATA. 



Beitish Localities oy Fossil Mammalia. 



The EniTOE, in opening this department of the magazine, earnestly 

 asks the assistance of every true geologist. In the provinces, geologists 

 must be the gatherers of materials which those resident in large cities, 

 from the association w^ith the chief talent of the day, and from, their 

 ready access to large collections of specimens, books, and other essential 

 aids, are placed in the best position to interpret. The generalizer in 

 geological matters cannot be, to any great extent, the worker in the 

 fleld ; and the Editor trusts that his magazine may be the link to 

 associate the labours of all who are interested in the progress of Geology, 

 1^0 one, in forwarding information on such points of inquiry as from 

 time to time will appear in this department, need hesitate on the 

 ground of any fancied inability, or on a supposition that the informa- 

 tion might have been conveyed by others. It w^ill be far better for us 

 to receive it in any form, or twice over, than not at all. The informa- 

 tion which we receive we shall tabulate or condense every three 

 monthS; or at such other periods as may be deemed most advantageous. 



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