Landslips and Sinkings in Cheshire. 259 



strong acid destroys crust and polyzoon alike ; warm water does not 

 dissolve it. The solution with weak acid was found, on testing, to 

 contain sulphuric acid ; it is therefore probably a layer of sulphate 

 of lime. The gradual diminution of the aperture seems to point to 

 the chemical origin of the crust, which has crept onward and has not 

 been allowed to complete itself till the death and final decay of the 

 last fragment of the polyzoon had removed the excuse for the infu- 

 soria and rotifers which "crept out and crept in." We have not had 

 time to inquire farther into the matter ; but if any one desires to 

 investigate the nature of this layer, we shall obtain specimens for 

 him. The interest of the question lies in the possible relation which 

 this layer may have to the Hemitrypa of Phillips. 



Vll. — Landslips and Sinkings in Cheshire. 



LANDSLIPS are important agents in modifying the surface of the 

 earth, frequently adding to the picturesque appearance of the 

 district in which they occur, and occasionally causing considerable 

 mischief by the destruction of villages, or the covering of fertile 

 ground, as the fall of Eossberg in Switzerland ^ in 1806, and in our 

 own country the landslip near Axmouth,^ and the undercliff of the 

 Isle of Wight, are familiar examples. They are generally caused by 

 the action of water dissolving or loosening and carrying away some 

 bed low down in the local series, when the upper strata, being no 

 longer supported, break by their own weight, and slide down to a 

 lower level, the amount of their displacement and the rapidity of 

 their movements being determined by the inclination of the under- 

 lying beds. 



Sinkings or depressions of the surface of the land may originate 

 in a similar manner, or the excavations may be artificially produced. 

 In our coal districts we may frequently observe great alterations of 

 the surface, due to the working of the coal beneath — the levels of 

 roads, railways, and canals are often disturbed, and not unfrequently 

 buildings erected on the surface are destroyed or seriously injured. 

 The extent of the sinking in these cases of course depends on the 

 depth and thickness of the seam worked, and on the resisting power 

 of the beds overlying it. 



In the salt districts similar phenomena have been long noticed, and 

 as the salt beds are much thicker than the seams of coal, the effects 

 produced by their removal are greater and more striking. Indeed, 

 so great is the threatened mischief, that the attention of the Board of 

 Trade has been called to it by the Salt Chamber of Commerce, and a 

 thorough official investigation of the facts has been made, resulting 

 in the production of a most important and interesting report by Mr. 

 Joseph Dickinson, F.G.S., which was presented to the House of 

 Commons during its last session. 



1 The villages of Goldau and Busingen, the hamlet of Huelloch, a large part of 

 the village of Lowertz, the farms of Uuter- und Ober-Eothen, and many scattered 

 houses in the valley, were overwhelmed by the ruin. Goldau was crushed by masses 

 of rocks, and Lowertz invaded by a stream of mud. The lives lost were estimated at 

 from 800 to 900. De la Beche, Geol, Observer, p. 22. 



2 Principles of Geology, p. 540. 



