Vol. 55.] TOKSIOlir-STKUCTUEE OF THE DOLOMITES. 601 



I regard the Campolungo-Pass exposure of Schlern Dolomite, 

 together with the irregular appearances of Raibl rock above it, 

 as fragments of underfolded strata which have been steeply tilted 

 down to the north-west, and twisted obliquely beneath heavy 

 overfolded masses with easterly flexure. The overlay of the fold 

 comprises the strata on the Pi an de Sass terrace and the summit of 

 Col di Stein. The underlay of the fold comprises the strongly- 

 sheared strata between the Campolungo Pass and the Bova Alp 

 corner (fig. 14, p. 592). 



According to this view, the needles of Schlern Dolomite which 

 stand upon the Campolungo Pass would represent on the east of Sella 

 another small sheared fragment below the peripheral overthrust, 

 offering complete analogy with the southern dolomitic fragment of 

 Sasso Pitschi ; and neither of these abrupt summits can be said, 

 upon the evidence of stratigraphy, to have arisen as individual coral- 

 reefs. 



Peripheral overthrust in the north-eastern part of 

 the massive. — Immediately north of the Pian de Sass terrace an 

 escarpment runs eastward from the imposing cliffs of Yallon to the 

 grassy col between Corvara and Campolungo. The escarpment 

 terminates abruptly against the small peak of Cra di Mont, the 

 eastern corner ('Cra') of the Sella Massive. The col below is some- 

 times called ' Corvara Col,' and sometimes erroneously ' Campolungo 

 Pass ' (p. 598). The escarpment is composed of the diagonal anti- 

 cline of Schlern-Dolomite rock and Paibl horizons, faulted against 

 the downthrown E,aibl strata and Dachstein dolomitic limestone 

 forming the high cliffs on the west. The strata of the escarpment 

 are crumpled and broken at intervals by flexure-faults. One well- 

 marked flexure occurs about the middle of the ridge, and bends the 

 strata very steeply eastward. Lago di Boe lies in the hollow of that 

 flexure, and is surrounded on all sides by Schlern Dolomite be- 

 longing to the same overthrust series as that on Pian de Sass. 



Another and more twisted flexure-fault occurs at a lower level. 

 In the hollow of it a small wedge of highly-tilted Cassian rock 

 occurs, which can be determined as a high horizon of marls and 

 encrinite-limestone. The Schlern-Dolomite peak of Cra 

 di Mont crops out below the Cassian wedge, and the 

 Schlern-Dolomite strata dip from 35° to 45° westward. 



The position of the Cassian rocks upon the Schlern Dolomite 

 indicates the passage of the peripheral overthrtist-plane, which 

 emerges here as a reversed fault-branch from the diagonal (north- 

 north-east by south-south-west) fault between Pian de Sass and the 

 Campolungo slopes. The diagonal fault continues its own direction 

 below Cra di Mont, and leaves the mountain at this point. It 

 penetrates Cassian and Wengen strata in a north-north-easterly 

 direction, but soon furcates again, 2"iving off another reversed fault- 

 branch in a north-north-westerly direction between the Piz terrace 

 and Crap de Sella, and itself continuing in a north-north-easterly 

 direction to the Eudort stream opposite Corvara. The diagonal fault 

 depresses the western portion, and is recognizable as one of the series 



