PRESIDENT S ADDRESS. 



but not many details have as yet been published. The 

 geographical effects were, as might be expected, very marked. 

 The whole charting of the Straits of Sunda, a very much 

 frequented highway for shipping, has been rendered useless, 

 islands have been thrown up, and others are partially removed, 

 shoals have formed, and others have disappeared. — (For a map 

 of the Straits, see "Nature," January 17th, 1884, p. 2G9.) 



Among the interesting and important matters which have 

 been discussed among geologists, two, somewhat connected with 

 each other, stand prominently out. As is well known, Sir R. I. 

 Murchison recognized in the hornbleudic gneiss of N. W. 

 Sutherland and the Hebrides a possible equivalent of the great 

 masses of gneiss to which American geologists have given the 

 name of Laurentiau. At any rate he found that these masses 

 were separated from the strata above them by such discordance 

 and unconformity that he ranked them as Pre-Cambrian. On 

 the edges of the crumpled and highly inclined foliated gneisses 

 he supposed that Cambrian strata, sandstones, and limestones 

 were deposited. These are comparatively little altered, but 

 are succeeded by another series of gneissic rocks, which, as 

 they apparently overlie a certain limestone containing lower 

 Silurian fossils, were mapped as Silurian, and were considered 

 as a good case of the change by metamorphism of shales and 

 grits into crystalline rocks. 



For some time past geologists have been coming to the 

 conclusion that the structure of the country is not so simple as 

 this account would imply. Many workers have given their 

 attention both to the relations of the rocks in the field and to 

 their minute structure, and during the past year both our 

 member, Prof. Lapworth, and our corresponding member, 

 Dr. Callaw^ay, of Wellington, who is already famous for his 

 researches among these old rocks, have published their con- 

 clusions. The ill-health which we all regret so much has 

 prevented the former from completing his papers in the " Geo- 

 logical Magazine " on " The Secret of the Highlands;'" but those 

 which have appeared, containing as they do the elementary 



