52 L. F, Harper — Evidence of Uplift. 



reached by spray only during storms. When they were planed 

 off, however, their surface must have been subjected to the 

 maximum erosive action of the waves, which, judging by the 

 depth of water, is probably about 10 feet below high-water 

 mark. 



A fourth proof of uplift is based on the presence of shallow 

 lagoons or lakes which occur at intervals along the coast and 

 are open to the sea only during exceptionally stormy weather, 

 or when they are artificially opened to allow iiood-waters to 

 escape. Along other parts of the coast are extensive tracts of 

 level, swampy land, containing fresh water — areas useful for 

 grazing purposes only during very dry seasons. They are 

 thought to represent ancient lagoons which have been raised 

 above sea-level. In favor of this assumption, it may be added 

 that fragments of recent marine shells are found along the 

 margin of these fresh-water swamps. 



That this uplift is comparatively recent is borne out by the 

 geological evidence available, for there is little doubt that the 

 intrusive dikes are of post-Tertiary age, and yet sufficient time 

 elapsed prior to the uplift to permit of marine excavation 

 along their courses to a maximum extent of 200 feet. 



A review of the evidence leads the writer to estimate the 

 amount of uplift as follows : 



1. Coastal shelves, formed 10 feet below high-water 



mark, now 4 feet above _ 14 feet 



2. Ancient blowholes formed at sea-level, now 16 feet 



above. After taking off for the shelf elevation 12 feet 



The total uplift is, therefore, about _ 26 feet 



Geological Survey, New South W^les, Australia. 



i 



