Rev. A. Irving — The Permian- Trias Question. 325 



unequal underground solution of more soluble strata, as in the case 

 of beds of gypsum in our midland counties and beds of chalk under- 

 lying drift in the southern counties, has led to a complete bouleverse- 

 ment of the stratification of the superjacent deposits ; and nothing 

 is more familiar to a German geologist than the phenomena known 

 as Erdfalle, which are simply local sinkings of the ground, owing to 

 unequal removal by chemical erosion of soluble underlying beds. 

 It would be difScult, however, if not impossible, for the most ardent 

 advocate of a theory, to imagine the inequalities produced by the 

 erosion of a lower set of beds, having taken place subsequently to 

 the deposition of another set of beds upon the top of them, while 

 the beds of the upper set have preserved a perfect regularity and 

 liorizontality of stratification even down to the very bottoms of the 

 hollows which they have filled. Yet this is the case at the junction 

 of the Zechstein and Bunterschiefer as it is exposed in numerous 

 sections in Central Germany, some of which I have described in 

 a paper recently read before the Geological Society. Again, such 

 underground erosion would leave a ragged and unworn upper surface 

 of the Zechstein limestones ; but in quarry after quarry I have seen, 

 on the contrary, the upper eroded surface of the Plattendolomit of 

 the Upper Zechstein, where it was laid bare in the quarrying opera- 

 tions, with the angles of its protuberances distinctly rounded off, 

 just as one might expect from the scouring action of the finer debris, 

 which must have been once suspended in the water and carried 

 along by the currents, which deposited the thinly stratified (in places 

 one may say laminated) materials of the Bunterschiefer. 



Those who will weigh the evidence carefully will find, I think, 

 that there is at least as gi'eat an unconformity between the Zechstein 

 and Bunterschiefer in many places in Central Germany as there is 

 in Lancashire between the lowest Bunter and the Magnesian Lime- 

 stone series, or as that upon which Mr. Aveline insists between the 

 lowest Bunter-strata and the Magnesian Limestone series in Notting- 

 hamshire. The evidence of a break in time between the Zechstein 

 and the Bunter is overwhelming : and it follows therefore, that 

 wherever, in following Murchison, I have spoken in my former 

 papers of a conformable sequence existing between the Dyas and 

 Trias of Germany, all that must now be considered as unsaid. 



I hold that this is far more than a quarrel about mere names. The 

 name ' Dyas ' may not be the best that can be found ; but the classi- 

 fication which is adopted by those who have applied the name is 

 undoubtedly that which coincides most closely with the facts of nature; 

 and in all our investigations of, or inquiries into, the history of this 

 earth, other considerations are bound to give way to this. The 

 objections which I have heard alleged against the name ' Dyas,' 

 while some of them scarcely deserve notice, apply with equal force 

 to the name ' Trias.' The two words are of similar origin, and they 

 are both connotative, as distinguished from geographical, terms. In 

 his ' Introduction ' Geinitz points out that, as Murchison had pro- 

 posed the term " Permian " (which he admits might be a good local 



