I 



190 Correspondence — Mr, A. W. Waters. 



tion. Some few years ago Dr. Mayer publislaed a paper, " Ueber die 

 Nummiiliten-Gebilde Ober Italiens," in which, he correlated the 

 Lower Tertiaries — which have in this peninsula their most import- 

 ant extension in the north-east, as in the Vicentine, and the present 

 may, to a certain extent, be looked upon as a continuation of that 

 communication. 



This is a translation of a note on a coloured map of the north- 

 western parts of Italy, which was presented to the Geological Society 

 of France in 1877, and refers to the Miocene and Pliocene forma- 

 tions which occur in Central Liguria. 



According to Dr. Mayer these Miocene and Pliocene beds, from 

 the Lignrian to the Astian, have here a thickness of 22,000 to 23,000 

 feet. When we consider how much more largely the last two etages 

 of the Tertiaries are developed in the South of Italy, we do indeed 

 see that the relative length of the Tertiaries has been but im- 

 perfectly appreciated. Nor, in considering the Cainozoic period, as 

 a whole, should it be forgotten that the Lowest Tertiaries are less 

 developed in Italy than in many places, and that, to get an idea of 

 the time during which Eocene formations were being deposited, we 

 must look to India. 



Prof. Mayer is now willing to increase the calculation as to time 

 of some of his etages, and thinks, for instance, he can now allow us 

 as a minimum for the Messinian 40,000 years instead of 25,000. 

 This may be satisfactory as far as we think it has any signification ; 

 but we must say that we have but little sjMxipathy with these 

 attempts to fix even a- minimum for each stage, until we are in 

 possession of more facts. Prof. Mayer, however, gives us his ideas 

 of time for each of his divisions. 



These papers show the importance of Mayer's attempts to intro- 

 duce a uniform nomenclature for the divisions of the Tertiaries, and 

 his terms, if generally introduced, would prevent us finding Italian 

 deposits called " Schlier," " Leithakalk," " Sarmatische stufe," etc. 



A. W. Waters. 



TERMINAL CUEVATURE IN WEST SOMERSET, ETC. 

 giK^ — You would oblige by finding space for a few remarks on a 

 very controversial paper by Mr. Ussher, which has just appeared in 

 the Quart. Journ. Geol. Soc. About ten years ago I communicated 

 a paper to the Geological Society on what I called the Terminal 

 Curvature of Slaty Laminse (principally on the flat summit of 

 Brendon Hill, Somersetshire), and suggested a number of causes for 

 the consideration of geologists, none of which I confidently advocated. 

 So far as I can remember, all the geologists who afterwards ex- 

 pressed their opinion on this and other instances of terminal curva- 

 ture agreed with me in preferring the idea that ice in some form 

 had been the moving agent, with the exception of Mr. Darwin, who 

 stated that he had attributed somewhat similar phenomena in S. 

 America to earthquakes. I will not occupy your valuable space by 

 controverting all the objections which Mr. Ussher has brought 

 forward to my suggestions; but on reconsidering the subject, I 



