32 



MEXICO, CENTRAL AMERICA, "WEST INDIES. 



ancient giants, is far more level, its uniform surface being broken onl}'^ by a few 

 knolls of low elevation. South-eastwards it develoj)s into the Bolson or "Purse " 

 of Mapimi, a vast sandy and saline basin, for the most part desert, about 40,000 

 square miles in extent. The Bolson de Mapitni is the Sahara of Mexico. 



South of this depression the ground rises, and the two border ranges are here 

 connected by intermediate highlands and the crests of a mountainous plateau. 

 South-east of Saltillo a first group of summits attains a height of 8,450 feet ; 

 farther south a peak in the mining district of Catorce exceeds 9,000 feet ; the crest 

 of the Yeta Grande in Zacatecas maintains an altitude of 9,200 feet ; the Cerro de 

 la Cruz, near Aguascalientes, is said to be exactly 10,000 feet high ; the Gigante, 

 or " Giant," near Guanajuato, exceeds it by 850 feet, while a neighbouring summit, 



Tig. 13. — Volcanoes of Mexico. 

 Scale 1 : 11,000,000. 



180 MUes. 



despite its name of Llanitos or " Little Plains," approaches 11,500 feet. Lastly, all 

 the northern part of the states of Queretaro and Hidalgo is occupied by a chaos of 

 peaks and cones, some of which are distinguished by their fantastic outlines. Such 

 is the Mamanchota (about 10,000 feet), the " Organos " of Actopan, so named 

 from its porphyry towers disposed like the gigantic pipes of an organ. 



• Owing to the sporadic disposition of the mountain masses scattered over the 

 plateau, they may almost everywhere be easily turned without having to be crossed. 

 It was thus that the migrating tribes and conquering hordes were able to advance 

 southwards by following the natural routes winding round Malinche and Popoca- 

 tepetl, and meandering amid the heights of Hidalgo, Queretaro, and Guan;jjuato. 



On the other hand the escarpments of the plateau are in many places extremely 

 difficult to scale, and especially to turn horizontally, owing to the deep barrancas 

 excavated in parallel lines along the sloiDes of the hills. In the districts where 

 jDumice and light scoriae are the prevailing formations, the running waters have 



