Notices of Memoirs — E. Stohr — Sulphur Deposits of Sicily. 221 



tions ; which, in their turn, have been puckered into earth- waves 

 which bear no relation to the old strikes of the crust. 



Faults, as might be expected, display a tendency to run parallel 

 with earth-waves. When the crust is being forced into sharp curves, 

 cracks will naturally occur at right angles to the lateral pressure. 

 Hence the faults which traverse Cambrian and Postcambrian strata, 

 being parallel to the newer flexures, will be transverse to the under- 

 lying Precambrian strikes. 



It is now easy to see how a pair of parallel faults traversing at the 

 surface rocks of (say) Silurian age, and cutting down through Cam- 

 brian and Precambrian strata, will account for the origin of Pre- 

 cambrian riclges with transverse strikes. The upheaval of the 

 isolated wedge, and the denudation of the overlying Cambrian and 

 Silurian beds, require no explanation. The continued prominence 

 of the ancient ridge would be secured by the superior induration of 

 its metamorphic or altered volcanic constituents. 



To distinguish mountains of this type from anticlinal and syn- 

 clinal ridges, the term plagioclinal 1 is suggested. 



This peculiarity of structure may prove to be of practical aid in 

 detecting Precambrian formations. A plagioclinal axis is not neces- 

 sarily Precambrian, but its transverse strike should suggest inquiry. 



The facts here announced militate against an extreme school of 

 geologists, who deny that faults have had any perceptible share in 

 shaping the landscape. They have certainly very largely contri- 

 buted to determine the scenery of South Shropshire. That the 

 original surface produced by great dislocations has been modified by 

 subsequent denudation does not materially affect the question. It 

 would be equally just to argue that, because the Romance words in 

 the English language have been modified by time, the Norman 

 Conquest has not affected our modern tongue. 



1TOTIGES OIF 1 ZMHEnVHOIZRS. 



I. — The Tufo and Tripoli of the Sulphur Zone op Sicily. 2 



TWO years ago Sig. E. Stohr, when placing the sulphur deposits 

 in the Messinian II. of C. Mayer, and the " tufo " in the 

 Messinian I., remarked that perhaps this last should be removed 

 lower down, and in the December number of the Bolletino E. Com. 

 Geol. d'ltalia he saj^s, that the discovery of fossiliferous beds in a 

 sulphur mine, near Grotte, in the Province of Girgenti, has confirmed 

 this opinion. 



Immediately below the sulphur beds is a bituminous schist, then 

 the tuff and tripoli, and in this "tufo," which is described as an 

 almost plastic clay, are a great number of Foraminifera, the subject 

 of Sig. Stohr's paper. Of the 115 species found, 23 are new, and 

 are mostly described and figured by Dr. Schwager in an appendix. 



1 From 7rAa7tos, oblique, and nxivw, to incline. 



2 Sulla posizione geologica del tufo e del tripoli nella zona solfifera, per E. Stohr. 

 Boll. R. Coniit. Geol. d'ltalia, vol. ix. No. 11-12, 1878. 



