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.JiUTTONIAN THEOPvY. 



277 



to be defcribed. The lower flratum, which is 

 feveral Swedifh miles in circuit, (loi of thefe 

 miles make a degree), is an arenaceous ftone, 

 horizontal, refting on granite, and having its 

 particles agglutinated by clay. The ilratum 

 above this is calcareous, full of the petrifadions 

 of marine animals, and above this is the trap. 

 Thefe three kinds of rock corapofe the greater 

 part of the mountains jult mentioned, though 

 there are fome other beds, particularly very thin 

 beds of marl and of clay, which feparate the 

 middle ftratura, both from that which is under 

 it and over it, and are frequently fo penetrated 

 with bitumen that they burn in the fire. This 

 fchiilus is black ; when burnt it becomes red, 

 and aftervyards, when wafhed with water, af- 

 fords alum. How can it be fuppofed," he adds, 

 " that the trap has ever been violently heated, 

 while the fchiilus on which it is incumbent re- 

 tains its blacknefs, which however it lofes by 

 the adtion even of a very weak fire *." 



The anfwer to this argument is already given. 

 The reafoning, as in the former inftance, is con- 

 clufive only againft the adion of volcanic hre, 

 or fire at the furface ; but not againft the adlion 

 of heat deep in the bowels of the earth, and un- 



S3 



der 



* Bergman de Produdis Volcaniis Opufcula, torn. iii. 



