75 



chief Dolomite moiintains, such as the Langkofl and Plattkofl Massive and 

 Sella Massive, are áreas of iathrow surroiinded by faults, within which 

 the higher thrust-slices ha ve been preserved. ' 



One of the geological maps shows foiu" successive thrust-masses — (1) 

 a basal thrust-mass TTiamly composed of the Permian Quartz Porphyry 

 and Groden Saudstones. the Lower Trias, and the "Galcareous facies" of 

 Muschelkalk and Marmolata Limestoue: (2) a thrust-mass comprising 

 fi'agments of the older strata and widely extended exposiu'es of the porphy- 

 ritic lavas and tufaceous and dolomite facies of Middle Trias; (3) a thrust- 

 mass belonging to the same facies as (2), but mainly composed of Schlem 

 Dolomite, with varying thicknesses of the lavas and tuffs below it and of 

 Upper Trias and younger horizons above it; (4) a thrust-mass mainly 

 composed of Upper Triassic Dolomite associated with infolds of younger 

 Mesozoic strata. The other geological map shows the datailed stratigraphy 

 of the Langkofl and Plattkofl Massive. Tliis mountain has been regarded 

 as a "C'oral-Keef" of Middle Triassic age, but the supposed "reef" peculiar- 

 ities are interpreted by Mrs. Gcjrdon upon the básis of the overthrust 

 structures typical of the whole área. The outstanding def ormational f eat- 

 ure of all the thrust-slices is the rapid variation in the thickness of the 

 various horizons of strata. Other features are the brecciated or nodular 

 structure of the rock-material in tlie crush-zones, passing into gneissose 

 and schistose structure. and the cióse cleavage penetrating the rocks in 

 intersecting directions. The outward dip of the strata noticeable in the 

 chief mountain-massives is a dip participated in by the subjacent thrust- 

 masses and associated with steep flexui-es towards leading faults of the 

 later period of do^vnthrowing and horizontal displacements. Mrs. Gordon 

 interprets the leading strike in the district as a curve round the north, 

 west and south, and the transversal directions as N.N.W.-S.S.E., N.S., 

 and N.N.E.-S.S.W., the system being es-sentially an interference system 

 produced in virtue of the coalescence of plicational effec-ts during the 

 interaction of north-south and east^west pressures 



