120 Taylor amd MoroMi— Sand-pipes in tke Chalk. 



Jt is Airtj' years ago ance Sr CSiades livell piopoTmde'i a theory 

 "wlik^ shooM explain the occnrrenee of saiid-pq)es, or •■ sand galls." 

 as <2i£y BIB termed in Xorfolk. in the Chalk sirata. Tt is scarcely 

 neoessazy to mention thas this was based on the power of perco- 

 lating water, slightly dialled with acid, to disolve and remoTe 

 masses of c^cazi^Mis materiaL Although this theoxy was comb^ed 

 \tj the late Mr. Stai^ of l!iarwich, w^ho endeavoured to explain tihe 

 UE^iu <rf sand-^pes in tiie (dialk: by referring them, to fissures or 

 czevices whidi had be^i sohseqaenQy widened, the explanation just 

 reSesEzed to, baeksd as it afterwards was by ihe res^iches of Mr. 

 Prestwidi, gradn^y passed into common acceptance. Lately there 

 has beai a disposition, on the part of sevez^ geologists, to aacdbe 

 many of tibese s^id-pipes to the mechanical action of miniatore 

 whirlpools triturating Ae bottom by flie grinding power of gravel 

 and coarse sand. We donbt not ^lat in some of ^e harder rocks 

 anaU hoUows may thus be formed, bnfc we are convinced that no 

 other ^leozy than that of chemical action will accoont for the large 

 and small sandr^^es in calcareous stzata. In the neigfabonrhood of 

 !$iotwJch. w^hae the Upper Bonlder-<3ay coniaina large quantities of 

 dalky rnbbl^ smaTl sand-pipes are common, showing that the 

 water has dissolved as nmch as it possibly conld of the calcareous 

 inatfirial . The thitily bedded Xorwich Crag ia &eqnentiy dissolved 

 away in a siTnilaT m^iner. and tin'-; phenomeii::i := =~"T more 

 common in tiie Bed and Coralline Crag districis. 



We r^azd these sand-pipes as so many natural drains. The 

 recent dasaScatifms whidt have been m^ie in Xorfolk geol<^y, 

 however, bear a distinct relation to the mode ia which sand-pipes 

 oocHr. In flie first place^ wherever we have the disturbed or 

 " gl ac i ated" Chalk, these p^pes are usually present in the greatest 

 mnnber. On tiie conbary, where the hard nii'listurbed Chalk comes 

 1^ sand-pipes aie of rarer oossGrr-z.:^. T^-. : r : i.: drainage excava- 

 tions prove that water percolates ^ery si;— It. .^r^i with great diffi- 

 culty, throng^ the re-depoa^ted Chatk. This gives the diluted acid 

 more time to operate, and as the Chalk is very much comminuted, 

 the Uqnid is better able to bk^ upcm. it^ owing to the number of sur- 

 :&ces thiK presented. Xn the h^rd or undisturbed chalk the water 

 sotmer dxaappesas, although in larger qo^mtities, tihroogh tiie various 

 joints and fissures, mid alor_gr 'Jie li : rJ! : - 1 al beds of fiint, ttntil it 

 readies the level rf satnrad.r. 



It is the re-deposited Cli 1: : Vs-lz—aiL" as it is called in 

 ^le vemacolar', which is '::;.-:: 1-:. ::-. the neighbourhood of 

 Norwidi by nnmeroxLs ^ i - ^ In - ;_t in-* -.-es the perco- 

 lating water has carrlT ' — n :nv :ir n i_ :ii .. :; portions of 

 oxide of iron, which L ~r —\:^ \: -: : ^ :::ain, and 



eemoited it more fiml- ::^r:.T. 7.; ^..ii. :; :_c :r-ieposited 

 Chalk, and thenmn-irr :: - _ - - found in it, are more or 

 less governed by ihe — rm :: '.'..=-. -— -. strata. As re:'- '^^ 



expected, tiiey are mc-n n::^^ :- ^ :?e consist of 



layeas of sai^ and g"- -! 7:; -iter readily n. - 



waytiuoog^tiiese, ai^: ^- n _ :lic- CTialk. 'S:i-r n^ . 



