300 
Geology of Sydney. 
lines of lofty cliffs. It is not easy to conceive a more 
magnificent spectacle than is presented to a person 
walking on the summit-plains, when without any 
notice he arrives at the brink of one of these cliffs, 
Fig. SI. View on the coast near Narrabeen, showing a fold in 
the Narrabeen Shales, caused by expansion of the underlying 
and the surface rocks as the result of weatheriug. 
which arc so perpendicular that he can strike with a 
stone (as I have tried) the trees growing at the depth 
of between 1,000 and 1,500 feet below him; on both 
hands he sees headland beyond headland of the 
receding line of cliff* and on the opposite side of the 
