Vol. 55.] TOKSION-STRTJCTUEE OF THE B0L03IITES. 585 



still in situ in the midst of the brecciated shear-rock. Contact- 

 alteration is everywhere evident along the many threads of intrusive 

 igneous rock. 



Specimens of the intrusive rocks have been kindly determined for 

 me by Prof. Watts. They include augite-porphyrite, and a variety 

 which might be described as olivine-melaphyre, together with a 

 variety of liebenerite-porphyrite. 



The chief occurrence of the intrusive rock is as a fault-sill 

 between a uormal fault inclined north and with northerly downthrow 

 and a reversed fault inclined north with southerly overthrust. It 

 has been injected into a ruptured ' knee-bend ' flexure of the rocks, as 

 at the Groden Pass. The figure also exhibits a transverse fault 

 cutting the inclined faults and seamed with a thread of intrusive rock. 

 The strata on either side of the transverse dyke have been strongly 

 sheared and altered. On the west side is the familiar shear-and- 

 contact breccia of Lower and Middle Trias ; on the east side the 

 Wengen Series is present, comprising true interbedded dust-tuffs and 

 lavas, as well as fossiliferous shales and shaly limestones. There is a 

 contact-zone not more than 12 inches wide, in which the Wengen 

 rocks have been altered to easily-powdered greenish pseudo-tuffs 

 answering to the general appearance of pietra verde. 



Oblique faulting across the Cherz overthrusts. — 

 The main overthrust is exposed chiefly in Muschelkalk horizons. 

 A lower overthrust can also be distinguished in some places, slicing 

 contorted fragments of the Werfen rocks along with the Muschelkalk. 

 Both are cut oft' on the middle slopes below Sella by the diagonal 

 north-north-westerly and south-south-easterly, or Campolungo 

 branch from the Pescosta Fault (p. 573). 



The most remarkable feature about the Cherz Hill overthrusts is 

 that the rocks have not been sliced along continuous planes, but 

 as a number of oblique torsion-wedges, each wedge showing a certain 

 individuality in the precise stratigraphical relations of the inclined 

 faults (see fig. 10, p. 586). A radiating bundle of these oblique faults 

 occurs behind Yarda, and has given the overthrust group of rocks 

 the twist which has carried them round to the west-north-west. 



The small area of Varda offers an example of a fold overcast 

 primarily towards the south, but sliced obliquely across its strike 

 into a number of movable pieces, capable of being twisted and set in 

 a new direction of strike, at the same time that the strains of com- 

 pression induced overthrusting. 



The Pralongia -Soraruaz diagonal fault. — An im- 

 portant vertical diagonal fault cuts the Pralongia meadows in 

 a north-and-south direction, crosses the Buchenstein Valley, and 

 curves south-south-westward near Soraruaz. This fault runs parallel 

 with the Campolungo Pault, and both throw down the strata on 

 the west : that is, towards Sella. The Soraruaz Pault marks also the 

 median line dividing the eastern and western portions in the torsion- 

 system of the Buchenstein anticline. 



Whereas the Arabba, or western part of the anticline, is charac- 

 terized by the exposure of an intruded sheet of porphyrite in the 



