x; up the Loire to Orleans, the Garonne to Toulouse and the Rhone to
Valence.[634] So the Atlantic rivers of North America formed the lines of
European exploration and settlement. The St. Lawrence brought the French
from the ocean into the Great Lakes basin, whose low, swampy watershed
they readily crossed in their light canoes to the tributaries of the
Mississippi; and scarcely had they reached the "Father of Waters" before
they were planting the flag of France on the Gulf of Mexico at its
mouth. The Tupi Indians of South America, a genuine water-race, moved
from their original home on the Paraguay headstream of the La Plata down
to its mouth, then expanded northward along the coast of Brazil in their
small canoes to the estuary of the Amazon, thence up its southern
tributary, the Tapajos, and in smaller numbers up the main stream to the
foot of the Andes, where detached groups of the race are still found.[635]
So the migrations of the Carib river tribes led them from their native
seats in eastern Brazil down the Xingu to the Amazon, thence out to sea
and along the northern coast of South America, thence inland once more,
up the Orinoco to the foot of the Andes, into the lagoon of Maracaibo
and up the Magdalena. Meanwhile their settlements at the mouth of the
Orinoco threw off spores of pirate colonies to the adjacent islands and
finally, in the time of Columbus, to Porto Rico and Haiti.[636] [See map
page 101.]

[Sidenote: Historical importance of seas and oceans influenced by their
debouching streams.]

So intimate is this connection between marine and inland waterways, that
the historical and economic importance of seas and oceans is noticeably
influenced by the size of their drainage basins and the navigability of
their debouching rivers. This is especially true of enclosed seas. The
only historical importance attached to the Caspian's inland basin is
that inherent in the Volga's mighty stream. The Mediterranean has always
suffered from its paucity of long river highways to open for it a wide
hinterland. This lack checked the spread of its cultural influences and
finally helped to arrest its historical development. If we compare the
record of the Adriatic and the Black seas, the first a sharply walled
_cul de sac_, the second a center of long radiating streams, sending out
the Danube to tap the back country of the Adriatic and the Dnieper to
draw on that of the Baltic, we find that the smaller sea has had a
limite