722 REPORT— 1892. 



are essentially the upward continuation of the Wengen teds, the two series to- 

 gether forming a sharply defined complex of very great tektonic importance in the 

 region of ' The Dolomites.' 



2. On a Granite Junction in Midi. 

 Bij J. G. GOODCHILD, H.M. Geological Survey. 



[Communicated by permission of the Director-General of the Geological Survey.] 



A quarter of a century back Professor Hughes expressed the opinion that 

 granites and some other intrusive rocks did not thrust aside the rocks they invaded, 

 but rather that they occupied exactly the same position, and that they replaced, 

 rather than displaced, an equivalent bulk of the rocks into which they had eaten 

 their way. At a later date Mr. Clough came to the same conclusion in regard to 

 Whin Sill of Teesdale. The idea did not find acceptance except amongst field 

 geologists, the chief objection urged against it being the remarkable uniformity of 

 composition of the invader where the rocks assimilated happene'd to present a wide 

 range of chemical composition. Mr. Clough sup-gested as an explanation of this 

 difficulty that the molten rock might have undergone circulation throughout the 

 mass as fast as it was melted up. 



The aatlior's examination of the peripheral parts of the Ross of Mull granite 

 (as well as of others in Cornwall and elsewhere) seemed to him to lend further 

 support to the views advanced by Professor Hughes and Mr. Clough. He considers 

 that the evidence is in favour of replacement by melting in the case of the majority 

 of intrusive masses, the molten rock being diS'used as an alloy throughout the 

 mass, but that where the superincumbent pressure was comparatively low he admits 

 tliat a true laccolite might really be formed, and the molten mass thrust into a 

 .space formed by local upheaval of the overlying rock without any such replacement. 



3. The St. Bees Sandstone and its Associated RocJcs, 

 By J. G. GooDCHiLD, U.M. Geological Survey. 



[Communicated by permission of the Director-General of the Geological Survey.] 



The author reviews the history of opinion upon the classification of the New 

 Eed rocks of Cumberland and Westmorland, and then gives the following as the 

 maximum thickness, general succession, and probable equivalents elsewhere of 

 these rocks : — 



A^ew Heel Series ( Upper Division). 



Maximum observed 

 thickness in feet. 



(5) Red marls with rock salt and gypsum .... 050 

 (•1) St. Bees Sandstone, with the following subdivisions : — 

 (<Z) Waterstones ; (<?) zone of tile red phases; (b) dull 

 Red Sandstone with local bands of iine con- 

 glomerate and occasional pebbles ; (a) zone of 

 variegated sandstones. In all ..... 2,000 

 (id) graduates downward into — 

 (3) Gypsiferous marls with local conglomerate at its base . 300 



Magnesian Limestone Group. 



(2") Magnesian Limestone .• . . . ..... 25 



(2') Plant beds . 150 



Lower Neio Red. 

 (1) Penrith Sandstone : the Brockrams .-. . . . 1,500 



Extensive TJno.onformity . 



There is a perfectly unbroken downward succession as far as tlie conglomerate 

 at the base of (3) ; and, therefore, as (4c) is admitted on ajl hands to be of Triassic 



