564 MISS M. M. OGILVIE [mES. GOEDON^] ON THE [Aug. 1 899,. 



to bring forward any conclusive evidence of the age of the younger 

 injection-dykes in the longitudinal faults of Enneberg. The 

 relationship in time of the younger injections with the younger 

 system of faults was highly probable, but this did not limit the age 

 of these injections to Tertiary time, as the crust-movements of the 

 atest Alpine upheaval were already advancing through the Eastern 

 Alps in Cretaceous time. Moreover, the dykes were found to be 

 cut by the transverse faults, which are the youngest faults of the 

 district. All that I was then in a position to say for Enneberg 

 was that ' It would seem that the Judicarian-Asta system of faults 

 followed largely ancient lines of weakness, which had been marked 

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

 of uncertain age.'^ 



Thus it remained to discover what was the relationship between 

 Triassic and Tertiary movements in the areas under observation^ 

 Further, though overthrust-shearing might account for the lenticular 

 shape of some of the mountains (as, for example, Sasso Pitschi), it 

 would not altogether explain the constant recurrence of circular and 

 elliptical mountain-shapes with precipitous walls of dolomite-rock, 

 composed of younger Triassic rocks, sunk in appearance into the 

 middle of swelling Alpine pasture-lands composed of older Triassic 

 rocks ; nor, again, the remarkable basin-shaped or C-shaped depres- 

 sions in the very heart of the massives themselves, containing twisted 

 masses of Jurassic or Cretaceous rocks in abnormal stratigraphical 

 relations to the Dachstein Limestone of Upper Triassic age. 



Three years' unabated work had only sufficed to show me that the 

 coral-reef theory was wrong, and that the explanation of the 

 phenomena by transverse and overthrust-faulting, so far as my 

 observations disclosed, was insufficient. Clearly some greater, 

 general cause lay behind all these features. I then spent two 

 years in visiting and studying as many other parts of the Alps as 

 possible, and thereupon returned to the Dolomites, to map, in 

 fuller detail, the area that immediately adjoins my previously 

 published map of Sett Sass and Pralongia. 



Eesults obtained in recent years by other inves- 

 tigators. — Before entering upon the description of the district 

 investigated and the new results obtained, it will be best to clear 

 the ground by pointing out the present state of knowledge and 

 opinion with reference to the facts and conclusions advanced in the 

 author's previous papers, some of these conclusions having been 

 strikingly corroborated by the circumstance that other observers in 

 the same field have arrived at results either identical or in perfect 

 agreement with them. 



In 1894, Prof. Eothpletz published his description of a com- 

 plete section across the Eastern Alps.^ A part of this section 



1 Op. cit. Geol. Mag. 1894, p. 58. 



^ ' Ein Geologiscber Querschnitt durch die Ost-Alpen, nebst Anhang liber die 

 sog. Glarner Doppelfalte,' Stuttgart, 1894. The present author has, in previous 

 works, acknowledged ber indebtedness to Prof. Rothpletz, first as a student 

 attending his lectures and afterwards in the free interchange of opinion. 



