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XLI. On the Structure of the Earth, and the Changes 'mhich 

 are continually passing upon it hy the constant Operation of 

 the Laws of Nature. Read before the Glasgow Philosophical 

 Society on the 29th of July 1822. By James Boaz, Esq.*' 



ON examining the structure of the earth, it is found to con- 

 sist of stratum sub stratum as deep as has yet been ex- 

 plored ; and mostly all having the appearance as if water had 

 been the principal agent in their formation. — Of these im- 

 mense masses of inert matter, there is another feature which 

 obtrudes itself on our attention, — whether the stratified beds be 

 of clay, till, sand, gravel, nmd, or other soft substance, or 

 coal, schistus, limestone, ironstone, or even the hardest rock ; 

 all have been subjected, more or less, to change of sitiis, either 

 upward, downward, or laterally. Thus, 



First. In some instances a whole district of land appears 

 to have been forced upward per saltum, or rather its conti- 

 guous or adjoining district depressed, as if what formerly 

 upheld it, had sunk, or been annihilated. These sits are well 

 known to miners ; when they lose their vein, it is usually by a 

 dyke or trouble intervening, and (unless acquainted with 

 the conterminous workings) they are often completely at a 

 stand, after they get through it, whether to dig for the lost 

 stratum above or below its former floor. They sometimes find 

 it again 10 feet higher up or lower down; sometimes 100, 

 and sometimes not at all ; as it has either cropped out to day, 

 descended past their reach, or otherwise unaccountably dis- 

 appeared. Between the parted masses there is almost always 

 a partition wall or dyke, several feet thick, consisting often of 

 calcareous, siliceous or metallic substances, which after the 

 disruption had interposed themselves, either in a dry or a 

 fluid state, to fill up the chasm. Some beautiful stalactitial 

 specimens of this kind may be seen at the Giants' Causeway 

 in Ireland. 



Second. Vertical separations, where immense rocks and 

 even also whole districts have receded laterally from each 

 other, without liaving produced any change in the relative 

 level of their respective strata. In these cases the chasms 

 have generally be^n filled with the same materials as those 

 produced by sits. 



Third. That exercise of Omnipotence, which produced the 

 vertical depressions and lateral recedings before alluded to, 

 must have occasioned these innumerable declinations of strata, 

 from the dead level, to all degrees of obliquity, every where so 



* Communicated by the Author. 



conspt- 



