30 



MEXICO, CENTRAL AMERICA, WEST INDIES. 



its three craters and intervening walls. The central oval-shaped cavity is over a 

 quarter of a mile in circuit and from 120 feet to 130 feet deep. 



The last great eruption of Orizaba appears to have taken place towards the 

 middle of the sixteenth century. About the middle of the present century vapours 

 and sulphurous jets were still ejected from the crumbling rocks, which were 

 peeling away like the plaster- work of some old ruin ; but these almost transparent 

 vapours were seldom visible from the lower regions. Yet an inner wall could be 

 seen, disposed obliquely in such a way that its slope was confused with that of the 

 mountain itself. In 1878 the igneous forces were entirely extinguished, and the 

 crater is now usually filled with snow, which is regularly collected as on Popocatepetl. 



Fig. 12. — Oeizaba Peak. 

 Scale 1 : 500,000. 



// ^^— Sfe^- rismcbo Jacale — •—- — **- ^- 



V'V<==^t oF CrpenW ch 



9 Miles. 



Parasitic cones are dotted over the slopes of Orizaba, as well as on the surround- 

 ing plains. These cones, from 400 to 500 feet high, resemble huge barrows, and 

 in fact are said by the natives to be funeral mounds erected over the remains of 

 ancient kings. All must have long been extinct, for they are now clothed with 

 forest growths, and the craters themselves have become filled with a dense vegeta- 

 tion. Nevertheless a still active crater lies in the Derrumbaderos group (10,300 

 feet) on the crest of a volcanic cone north-west of Tepetitlan. 



Orizaba is not the terminal cone in the Mexican igneous zone ; beyond it an 

 isolated volcano, Tuxtla, 4,950 feet high, stands on the seashore near the extreme 

 curve formed by the Gulf of Mexico between the mainland proper and the Yucatan 

 peninsula. Tuxtla lies 135 miles in a straight line from Orizaba, and it is separated 

 from the Sierra Mad re system by extensive tracts of alluvial soil watered by several 

 streams. In 1664 it discharged some molten lavas, and was then quiescent till the 



