CHAP. XXI.] 



NEW ZEALAND. 



443 



The geological structure of these islands has a decidedly 

 continental character. Ancient sedimentary rocks, granite, 

 and modern volcanic formations abound ; gold, silver, copper, 

 tin, iron, and coal are plentiful ; and there are also some con- 

 siderable deposits of early or late Tertiary age. The Secondary 

 rocks alone are very scantily developed, and such fragments as 

 exist are chiefly of Cretaceous age, often not clearly separated 

 from the succeeding Eocene beds. 



MAP SHOWING DEPTHS OF SEA AROUND AUSTRALIA AND NEW ZEALAND. 



The light tint indicates a depth of less than 1,000 fathoms. 

 The dark tint ,, „ more than 1,000 fathoiiiS. 



The position of New Zealand, in the great Southern Ocean, 

 about 1,200 miles distant from the Australian continent, is very 

 isolated. It is surrounded by a moderately deep ocean ; but 

 the form of the sea-bottom is peculiar, and may help us in the 

 solution of some of the anomalies presented by its living pro- 

 ductions. The line of 200 fathoms encloses the two islands 

 and extends their area considerably ; but the 1,000-fathom 

 line, which indicates the land-area that would be produced if 



