PHYSICAL GEOGEAPHY. ' xxyii 



rjggQ^^i^jradiially, though, iineyenly, towards the Bio Colorado; and 

 gj^-^jidirectly towards the Gulf of California. A remarkahle 



and tlif^P^^^s^o^ occurs ahout latitude 36^, which is separated both 

 . ^^ g^om the Eio Colorado and the Gulf by table-lands varying 



1 height from 1,000 to 6^000 feet above its lowest portion. 



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'^jgfhis depression is known as Death Yalley. 



^ kaski I^^fty table-lands extend also over all I^ew Mexico and 



Tlie inoM'^*^-^^? ^^^ gradually fall away towards the mouth of the Rio 



^^ i jjHla and the Gulf of California, in the south-west angle of the 



f rrrate?''tter territory. In Southern IS'ew Mexico the entire country 



1 1 aiix?*^^™^^ depressed into an extended plain,* about the 32nd 



7*'. ^I^l^rallel, having an, average elevation of from 3,500 to 4,000 

 I i^^^et. The depression, however, does not extend south more 

 . ^an fi'om fifty to one hundred miles before the general rise 



AAfl fee^^^^^^^c^^j which foims the lofty savannas of Mexico, upon 

 ^ rja^^t^ch the mountain ranges of that country rest. 



I West of the Sierra iN'evada of California, the land slopes 



' gipidly towards the west coast. K'atm'e has, however, placed 



" , J banier in the way by thi^owing up a series of ranges along 



^ he coast, known as the coast ranges. They run for the most 



-j^art parallel to each other, but obliquely to the coast, so that 

 ^^ .y^^D^ ^ft^^ range becomes lost in the sea, forming prominent 

 1^^^ ' eadlands and rocky islands all along the shore. About the 

 ii* ^ . entre of the Californian coast, a great gap occurs in these 



' fflipelf * The "first promoters of the grand scheme for uniting tlie Atlantic and 

 1^ *acific by a rail"WBy crossing the continent in United States territory seem to 

 CS^ave laid great stress upon the importance of this depression. They affirmed, 

 A . r nd with truth, that if the waters of the Atlantic and Pacific were to rise 

 j{ ^'lU^'^o the height of 4,000 feet, they would meet about the 32nd parallel, leaving 

 l^jlwo huge islands, the one to represent the lofty plateaux and mountains of the 

 tf^S _ Vestern territories, the other the still more elevated plateaux of Mexico. They 

 4gr Si^hought it probable that this depression would prove to be the only practicable 

 " ^ , ipute for the Pacific Eailway, and on that account urged the United States 

 a W^ tovernment to .buy it from Mexico. This was done on the 20th of June, 

 ■rtrt afl^ ^^"^ ' *^^ million dollars were paid for it, and the official document fixing the 

 ^^ -m boundarv is called the Gadsden Treaty. 



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