94 Part II. Chapter ı. 
development in the United States. Between the two is a broad basin 
drained by the Mississippi River, the Great lakes, the Mackenzie River and 
streams that debouch in Hudson’s Bay. 
The Cordilleran system may be divided into the Rocky mountain ranges, 
the Sierra Nevada ranges and the Coast ranges, which penetrates Mexico 
reaching to the Isthmus of Tehuantepec. South of Tehuantepec, the mountain 
system, although in part continuous with the cordilleras of the north, may yet 
be looked upon as distinct, for it runs almost due southeast and east, and in 
Yucatan the mountains trend in the same general direction, as those in the 
greater Antillean islands, viz., Cuba, Jamaica, Santo Domingo and Puerto Rico, 
and may be called the Antillean orographic system. East- and west-mountain 
ranges of the Antillean type occur through the Greater Antilles, along the 
Venezuelan and Columbian coast of South America, north of the Orinoco, in 
the Isthmus of Panama, Costa Rica, and the eastern parts of Nicaragua, Guate- 
mala, Honduras, Yucatan, Chiapas and southern Oaxaca. The two elongated 
submarine ridges, separated by the deep oceanic valley known as Bartlett Deep, 
which stretch across the Caribbean from the Antilles to the Central American 
coast, from the west end of the Sierra Nevada range of Cuba to the coast of 
Honduras, and from Jamaica to Cape Gracias a Dios, respectively, are similar 
in configuration to the east-and-west mountain ranges of the Great Antilles, 
and are, no doubt, genetically a part of them. 
The Gulf of Mexico is an indentation into the North American continent, 
the restricted survival of a great interior sea, which once extended over the 
Mississippi plain region of the United States, which at one very old time, 
almost, if not entirely, separated North America into two great continents, the 
Appalachian and the Cordilleran. The basin of the Gulf is still filling up with 
the material brought down by rivers, which drain nearly one fourth of the 
area of the United States. With the single exception of its extreme south- 
western indentation upon the coast of Mexico, the Gulf is surrounded by low 
plains. 
The Atlantic coast has, on the whole, a tolerably straight course in a 
direction nearly south-west; but in detail, it is greatly indented with numerous 
deep bays and harbors, and fringed by many islands. The north-eastern coast 
is rocky with deep fjord-like bays, and islands formed by depression of a more 
extended coast-line. South of and including Cape Cod, the character of the 
coast changes to a low sandy shore, and this character is maintained thence 
southward and around the Gulf. Along this part of the coast extends a line 
of narrow, linear islands, which are sand-bars thrown up by the waves, behind 
which are many shallow bays and salt marshes. The Pacific coast is muc 
less indented. It is very abrupt, rising from the shore for thousands of feet 
to the summits of the coast mountains and descending beneath the surface 
abruptly to great depths. It has few harbors San Francisco Bay, Puget Sound 
and Gulf of California being the largest ones. The Alaskan coast resembles 
in many ways that of New England, but its features are on a much larger 
