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favourable circumstances, the hall being quite filled with an 

 audience interested in the study of geology. 



The President briefly introduced the Lecturer. 



Professor Grenville Cole proceeded, after a few introductory 

 remarks, to show how, by a series of simple observations, mainly 

 in the open air, the past history of a district may be worked 

 out. This history, preserved in the rocks, is intimately and 

 necessarily connected with human history, and geology can 

 now be no longer ignored by the student of peoples any more 

 than by the student of geography. The earliest observations 

 into the materials of the earth were made by pre-historic men 

 seeking suitable stones for implements ; then followed the 

 search for native metals, and the discovery, probably made 

 accidentally around a camp fire, that certain ores were capable 

 of being smelted and of producing metals quite unlike them in 

 appearance. Rocks were also selected for use in building and 

 for ornamental work, as in the early Italian churches ; and 

 finally it became felt that, beneath their external differences, 

 there lay some difference in their mode of origin which might 

 be worth inquiring into. It was then seen that rocks were 

 made of distinct minerals, and that sometimes one kind, some- 

 times several kinds, were associated in the same mass. The 

 Lecturer proceeded to define the terms mineral and rock. 

 Rocks are made of mineral particles, minerals of chemical 

 molecules, molecules of atoms of chemical elements. Only 

 some eleven of the seventy known elements form any import- 

 ant part of the crust of earth. Similarly, the common rock- 

 forming minerals are few, nineteen species being mentioned 

 in the lecture. Minerals crystallise out from solution, from 

 sublimation, or from fusion. Rocks are made from materials 

 once held in solution, from materials laid out by winds or 

 waters (sedimentation), or from fusion, as in the case of lava 

 streams. At the present time the crust of. the earth was only 

 known to a depth of about fifteen miles, and this depth had 

 been obtained, not so much by the mining and boring of man, 

 as by the upheavals of the earth's surface, which rendered an 



