510 SIDNEY POWERS 
is 1,000 to 4,000 feet and the height of some more than 5,000 
recta . 
Plateaus. and irregular ridges of low relief, but with elevations 
of 3,000 to 4,000 feet, are found west and southwest of the mountains 
composed of metamorphic rock. This region is composed of early 
Tertiary or possibly late Mesozoic volcanics.? In places folded 
sedimentary rocks appear with the volcanics. Farther inland and 
nearer the Pacific Coast the ridges of folded volcanics give way 
to broad plateaus that are 3,000 to 4,000 feet above sea-level and 
are separated more or less completely from one another by rims of 
low hills. The plateaus slope gently toward the east. Young, 
deep gulches are rapidly dissecting the plateau surfaces. Exposures 
thus made show that the surfaces were formed in an earlier cycle 
of erosion by overloaded streams under conditions of aridity and 
that deep incision is now taking place for the first time. The 
summit of the plateau forms the continental divide—a volcanic 
plateau on which stands Guatemala City at an elevation of 4,900 
feet. 
On the Pacific slope in Guatemala the high plateaus are bounded 
by a row of active and recently extinct volcanoes which rise in many 
cases directly to elevations of 10,000 to 13,513 feet from the low 
plain that forms the coast. The alignment of the volcanoes is 
parallel to the coast and diverges sharply from the trend of the 
older mountain ranges. The plain at the coast is composed of 
volcanic ejectamenta and shows no signs of uplift; hence it would 
not be called a coastal plain according to some definitions of that 
term. It is so level that 20 miles inland, at Santa Maria, the 
elevation is only 416 feet. From here the surface gradually rises to 
an elevation of 1,100 feet at Escuintla, 27 miles inland. Only 40 
miles inland the dormant volcano Agua, near Escuintla, is 12,140 
feet high. 
«Elevations of 8,000 feet for Congrejal and Bonita peaks, near La Ceiba, 
Honduras, as given on a chart of the U.S. Coast and Geodetic Survey, evidently 
should be 4,000 feet. 
2 Vulcanism is thought to have begun during the Eocene in Mexico (J. G. Aguilera, 
Compte Rendu [roth Int. Geol. Cong., Mexico, 1906], p. 1157) and to have been in 
progress during the Oligocene in Nicaragua (C. W. Hayes, quoted by Sapper, Ze7t. 
Ges. f. Erdkunde [Berlin, 1902], p. 513). 
