CRIGH CLIFF. 



97 



cut at S. In tliis instance we have the effects of protrusion, and the 

 cause, displayed in the same hill. It is true, the black compact 

 toadstone had not been reached in 1830, but a great mass of indura- 

 ted green earth, which always accompanies it, and is regarded by 

 the miners as toadstone, and is called by the same name, had been 

 penetrated many yards. It was so hard as to require blasting. On 

 one side of this hill is what is called a pipe vein or opening between 

 the strata, filled with metallic ore.. This is represented in the cut at 

 d; the workings in this vein, have been continued nearly round the 

 hill. Near the top of the hill there are quarries worked, which dis- 

 play the strata rising towards the summit on each side. Having 

 shown that the mountain limestone of Derbyshire assumes, in many 

 parts, the arched stratification, it may easily be conceived how per- 

 sons, not aware of the circumstance, may have fallen into great mis- 

 takes in attempting to describe the succession of beds along a certain 

 line ; for the same beds, if arched, may rise near the surface, or 

 above it repeatedly, in the same country. (See Plate I. fig. 2.) 



Other effects of the proximity of trap or toadstone on limestone 

 will be noticed in Chap. IX. 



I cannot omit, before leaving the mountain limestone of Derby- 

 shire, to cite an instance of the influence which erroneous observa- 

 tions, combined with false theories, may have in retarding the pro- 

 gress of geology. Some years since, when it was the prevaihng de- 

 sire of many English geologists to make the different rocks agree with 

 Werner's arrangement, and they were perplexed how to dispose of 

 the mountain limestone — whether to place it in the transition class, or 

 what were called the floetz rocks (or flat rocks,) in which class were 

 included the upper secondary strata — an eminent chemist from the 

 North country, who affected a profound knowledge of geology, went 

 into Derbyshire to decide the question, and observing the strata op- 

 posite Madock Bath to appear horizontal, he published an oracular 

 opinion that the limestone of Derbyshire, was floetz ; and this opin- 

 ion continued for some time to mislead the followers of Werner in 

 this country. Now, had this observer taken the pains to obtain a true 

 section of the strata, he might have discovered, that instead of being 

 flat, they were inclined at an angle of thirty or forty degrees. (In 

 Plate I. fig. 6.) The strata, seen in the line of bearing do ap- 

 pear horizontal, whereas the section in the line of dip shows their 

 true elevation. Nothing, however, can be more puerile than to form 

 a classificadon of rocks, on a circumstance so variable as the position 

 of the beds ; and the name floetz is now banished from geology.* 



* We are not, however, free from the effects of this erroneous classification. 

 Some English geologists, finding that the characters of mountain limestone agreed 

 with that of transition limestone, but in awe of the decision which pronounced it 

 to be fxoetz, invented a new name, Carboniferous limestone, which is singularly in- 

 appropriate. 



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