ISLANDS.

 

389

 

general shape of the continents is mainly triangular. An
excellent system of map-drawing has been devised on this
peculiarity.

The following peculiarities exist in the coast
lines of the continents:

The coast lines of the northern continents are
very irregular, the shores being deeply indented
with gubfs and bays, while those of the southern con-
tinents are comparatively simple and unbroken.

The continents are most deeply indented near
the regions where the pairs of northern and south-
ern continents are nearly separated from each
‘other. These regions correspond with the lines of
great volcanic activity, and appear to be areas over
which considerable subsidence has occurred.

The continents differ greatly from one another
in their indentations. Europe is the most indented
of all the continents. The area of her peninsulas,
compared with that of her entire area, is as 1 to 4.
Asia comes next in this respect, the proportion
being 1 to 53, while in North America it is but
1 to 14.

The following Table gives in the first column the area
of each of the continents, in the second the length of coast
line, and in the third the number of square miles of area
to one mile of coast line:

 

 

Sq. m. of

CONTINENTS. AREA. COAST LINE. ee

of coast.
AGI Alesccessessscesess 17,500,000 sq. miles. |35,000 miles.| 500
AfTICA wecccseeseeees 12,000,000 16,000 750
North America..| 8,400,000 “é 22,800 “ 368
South America...| 6,500,000 . 14,500 “ 449
Europe... 3,700,000 sf 19,500 “ 190
Australia......... «| 3,000,000 s 10,000 “ 300

 

Europe has, in proportion to its area,
About three times as much coast line as Asia. ©
About four times as much as Africa.
About twice as much as North America.
More than twice as much as South America.
Europe is the most, and Africa the least, deeply
indented of the continents.

—-0503 00 ——_.

CHAPTER III.

Islands.

89. Relative Continental and Insular Areas.—
Of the 53,000,000 square miles of land, nearly
3,000,000, or about one-seventeenth, is composed
of islands.

90. Varieties of Islands.—Islands are either
continental or oceanic.

Continental Islands are those that lie near the

 

 

 

shores of the continents. They are continuations
of the neighboring continental mountain-ranges
or elevations, which they generally resemble in
geological structure. They may, therefore, be re-
garded as projections of submerged portions of the
neighboring continents. Continental islands have,
in general, the same lines of trend as the shores of
the neighboring mainland.

Continental islands, as a rule, are larger than oceanic
islands. This is caused by the shallower water in which
continental islands are generally situated. Papua and
Borneo have each an area of about 250,000 square miles;

either of these islands is more than twice as large as the
combined areas of Great Britain and Ireland.

91. American Continental Island Chains.

(1.) The Arctic Archipelago comprises the
large group of islands north of the Dominion
of Canada. It consists of detached portions of
the neighboring continent.

(2.) The Islands in the Gulf of St. Lawrence
and its neighborhood are apparently the northern
prolongations of the Appalachian mountain-sys-
tem.

(3.) The Bahamas lie off the south-eastern coast
of Florida, to which they belong by position and
structure. Their general trend is north-west.

(4.) The West Indies form a curved range,
which connects the peninsula of Yucatan with
the coast-mountains of Venezuela. Here both
trends appear, though the north-western pre-
dominates.

 

 

 

Fig, 33, West India Island Chain.
1, Cuba; 2, Hayti; 3, Jamaica; 4, Porto Rico; 5, Caribbee Islands;
6, Bahamas.

(5.) The Aleutian Islands form another curved
range, which connects the Alaskan Peninsula with
Kamitchatka; their general trend is north-east.
They are connected with the elevations of the
North American continent.