58 Miss M. M. OgiMe— Coral in the ''Dolomites.'' 



be extended to include the meadows of Prelongei, for in them I 

 found intrusive sheets penetrating high horizons of Cassian strata,^ 

 and producing contact-metamorphism in sedimentary beds above and 

 below. At Groden Joch,^ and in the Buchenstein Valley, dykes of 

 porphyry occur in Lower Trias and Wengen horizons. Where 

 they pass through Upper Muschelkalk, they have converted it in 

 situ into a brecciated rock, or sheared it into shaly layers. Both on 

 Groden Joch and on the Buchenstein cliffs the porphyry is exposed 

 in the main fault-lines which cut through these two anticlines of 

 older Trias. In the Buchenstein Valley, above Varda, the volcanic 

 rocks are hopelessly mixed up with the overthrust beds of Lower 

 and Upper Muschelkalk and Buchenstein strata, but they are absent 

 in the highly-folded succession of the same rocks below the thrust- 

 plane, at Ruaz, or in the series of radiating faults below Pieve. 

 Further detail I cannot give in these pages ; I would only indicate 

 the natural considerations which suggest themselves with regard 

 to the age of the intrusive sheets. Two hypotheses may be stated: 

 — (1) The intrusions of Augite Porphyry in these cases may be of 

 Triassic age, exposed along with the Triassic rocks through which 

 they penetrated, by later faulting and erosion. Since they, as well 

 as the lavas of distinctly Wengen age, often occur along the path of 

 faults, it would seem that the Judicarian-Asta system of faults fol- 

 1 )wed largely ancient lines of weakness, which had been marked by 

 the outbreak of lavas in Triassic time, or intrusions of porphyry of 

 uncertain age. (2) The idea that the intrusions may have been 

 associated with Tertiary movements in the Alps is not supported in 

 Enneberg, but rather the evidence shows that at this period the 

 volcanic rocks, both contemporaneous and intrusive, behaved as a 

 compact, united mass, along with the sedimentary rocks. 



The Buchenstein Valley finds its tektonic continuation in the 

 Pordoi and Eodella district, where, as a previous quotation shows 

 (p. 53), the facts appear to be in the main analogous. If we 

 now compare the great "Eruptive Fault" of Fleims and Fassa, 

 we find that by its throw at Sattel Joch, the northern wing 

 of the fault is Lower Trias, faulted to the same level as Schlern 

 dolomite on the south. The " Eruptive Fault " changes in its 

 relations at Viesena, but it may be traced east and west through 

 the country to a considerable distance from the actual eruptive 

 centres. Here and there along its main line or its radiating 

 branches, dykes of porphyry and melaphyre occur, just as in the 

 fault-lines further north. I should think there could be little doubt 

 that these great longitudinal fault-lines, together with the parallel 

 Villnos fault in the north, were developed under the same general 

 conditions, and were for the most part of pre-Tertiary origin. 

 These faults have all been important planes of movement since 

 Mesozoic time. Tertiary faults in some places coincide with, or 

 cross at varying angles, lines of Triassic disturbance. Where areas 



1 Q.J.G.S. 1893, loc. cit. p. 18, Map A. 



2 Cf. von Richthofen, loc. cit. p. 133, etc., who notes the occurrence of intrusive 

 rocks at Groden Joch. 



