THE OCEAN AND ITS WORK 



211 



Stacks, Skye, 



land, as is illustrated by Perce 

 Rock in Quebec (Figs. 196, 

 197), or (2) by the partial 

 collapse of the roof of a cave. 



Stacks. — Waves sometimes 

 quarry along strong joints, 

 leaving isolated portions of 

 cliffs in the form of chimneys 

 or stacks (Fig. 198). Stacks 

 are also formed by the falling 

 in of the top of a sea arch (Fig. 

 199). High stacks and chim- 

 neys are most common in hori- 

 zontal or gently inclined beds, 



where the strike (p. 253) coincides with the general trend of the coast. 

 The Old Man of Hoy on the coast of the Orkney Islands is a well- 

 known example. This is an angular column of red and yellow sand- 

 stone, more than 600 feet high. Many examples of such structures 



are to be seen on 

 the rocky shores of 

 New England and 

 Nova Scotia, in the 

 Bermuda Islands, 

 and on the shores of 

 Lake Superior. If 

 the rock is resistant, 

 the stacks withstand 

 the battering of the 

 sea for many years, 

 and as the sea cliffs re- 

 treat, may be left be- 

 hind as rocky islets. 

 Marine Terraces. 

 — As waves cut back 

 a shore, they develop 

 a submarine terrace 

 (Fig. 200) which ex- 

 tends from the base 

 of the cliffs and slopes 

 gently seaward until 



— ^r-^cr-r- ;;. Xq^ ^bM^ 



Fig. 199. — The Burgermeister Gate: A in 1864, and 

 B in 1899 after the arch had fallen leaving a stack. 

 (Drawing after Andersson.) 



