and Igneous Rocks of Ensay. 119 



level, while on the east side the massive igneous rocks rise 

 in a vast tract of mountains to some 4000 feet higher in the 

 Nunnyong tableland. One cannot tell to what depth the 

 contact plane sinks on the western side of the Tambo River, 

 or to what former elevation it rose at Nunnyong on the 

 north-east. 



The plane of contact is as irregular in the small scale as in 

 the large. In the few places where I have been able to 

 inspect it in vertical sections I have observed that the 

 invasive plutonic rocks have affected the sediments in a 

 manner which I can best illustrate by likening it to the 

 action of warm water upon masses of ice. They appear to 

 have eaten their way upwards in an irregular manner, leaving 

 portions of sediment hanging down or detached in the heated 

 materials* That this action has been accompanied by great 

 pressure of the molten masses against the sediments is 

 evidenced by the fractured and, so to say, " dog-eared" state 

 of the beds where they strike or dip against the former, and 

 by the constant occurrence of masses and veins of the intru- 

 sive rock penetrating the sediments. 



It is not necessary to consider whether this pressure 

 was by expansive forces acting from beneath upwards, or 

 whether it was by the downward pressure of parts of the 

 earth's crust upon the molten masses, or by both combined. 

 All that I am concerned with now is to point out the fact, 

 that the action of the invasive plutonic rocks has been to 

 force themselves, or to be forced, into the lower parts of the 

 sediments, and to gradually metamorphose, melt off, and 

 absorb them. 



As seen at Ensay, the first igneous rocks which were forced 

 into the sediments as veins and masses were varieties of 

 aplites, which either penetrated between planes of bedding 

 (foliation ?) or through cross fractures. In some places these 

 aplite veins are very numerous, so that in a horizontal section 

 they appear as small isolated masses surrounded by the 

 schists, or as veins crossing or apparently interfoliated with 

 them. 



Following the aplites were those masses of plutonic rocks 

 which are now the holocrystalline quartz-mica diorites. 



The whole complex of rocks, metamorphosed sediments, 

 veins, and masses of aplite and quartz diorite -have been 



* I have given a sketch of such an occurrence at p. 77, Progress Eeport, 

 Geological Survey of Victoria, Part II. 



