50 



members of the Bournemouth Students' Association and others 

 who had taken tickets for the University Extension course. The 

 summary of points described and discussed at each class, as given 

 below, is naturally a resume of Mr. Spicer's lecture, and it is hoped 

 will be of interest as a memento of this very important Course, and 

 also as a brief outline of the principal facts upon which our know- 

 ledge of this fascinating subject is based. The books upon the 

 subject recommended to be studied were Marrs Science of Scenery^ 

 Green s Physical Geology \ and Lubbock's Scenery of the British Isles. 



The first meeting of the class for this study was 

 Genera heM by Dr> 0rd Qn Wednesday, February ist, at 



the n Scien S ce of the Societ y' s ^ooms. The leading points elucidated 

 S n v were as follows : — Scenery is defined geologically 



as rock modified by certain agents. Scientifically, 

 " rock " includes all substances composing the solid constituents of 

 the earth's crust. There are two great agents which have modified 

 " rock " into "scenery " — (i) earth-movements, and (2) water. 



(1) Earth-7novements occur in two directions, either radially to 

 the earth's circumference, or tangentially to the same. These move- 

 ments are rendered possible by the earth having a mobile layer 

 underneath the crust and supporting it. Radial movements are 

 naturally "up and down," and tangential are along the earth's 

 surface or parallel to it. When great masses of the crust have 

 sunk down, leaving higher portions, these latter are called " horsts." 

 Some of the Continental plateaus are horsts. The ocean basins are 

 master segments which have sunk downwards, squeezing up 

 slightly domed-shaped continents between them. Table mountains 

 are smaller examples of the same process, when these have not 

 been caused by denudation. Around these masses the crust cracks, 

 forming rift valleys, which are bounded by lines of faults. 



The second, or tangential, form of earth movement forces 

 portions of the crust over other portions, forming "thrust planes," 

 which are bounded by " thrust faults," of which we have a 

 magnificent example in the chalk cliffs of Ballard Down. These 

 thrusts may continue to form " over-thrusts," as in the Alps, where 

 huge mountain masses have been so produced, or they may be so 

 small as to appear in hand specimens of rocks. 



The two islands of New Zealand show remarkable examples of 

 these forces, the North Island being a horst or continental dome. 

 This has been squeezed up by sunken masses of the earth's crust 

 in the ocean around it, the pressure being relieved by volcanoes in 

 the centre of the island. The South Island is also a horst, but 

 having no volcanoes, the pressure exerted upon it by the surround- 

 ing sunken segments has folded, faulted, and twisted its rocks into 

 many complex forms, squeezing them up into almost Alpine 

 mountains in the interior. 



Denudation is the second great producer of Scenery, and acts 

 almost entirely by water ; wind may play a small part in denudation 

 under certain conditions. Water denudes rock in three principal 

 ways : by (1) erosion, (2) by chemical solution, and (3) by mechanical 



