The universal geography : earth and its inhabitants

THE ARGENTINE UPLAND. 863
same normal direction, and all standing on the same pedestal 1,500 feet above the
plains. In general these crystalline mountains present, like the Andes, their
steep face towards the west, and slope gently eastwards down to the pampas.
A first ridge, traversed by the streams descending from the central system,
generally falls below 3,000 feet except at a few rare points, and culminates in
the Cuinbre de la Cal (5,150 feet) north-west of Cordoba. But the central chain
attains in the Champaqui peak a height of over 7,550 feet. In the north-west
the system merges in a plateau crossed by a line of volcanoes running east and
west, and terminating abruptly in the trachytic Cerro de Yerba Buena, which
rises 5,400 feet above the western plains. It has no apparent crater, nor has it
emitted lavas or vapours in the memory of man ; but slight earthquakes are
occasionally felt in the neighbourhood, and underground rumblings are also said
to be heard at the foot of these mountains.
The Sierra de San Luiz, or de la Punta, from its south-western spur, may be
regarded as forming part of the Central or Cordoba system, which dies out
northwards in the saline depressions. On their western and northern sides the
San Luis heights present the aspect of bold mountain masses ; but these escarp-
ments merely serve to mask a hummocky plateau, which in many places assumes
the character of a simple tableland. Amongst the highest peaks of the escarp-
ments are Monigote (6,430 feet), and the Gigautillo, " Little Giant," which faces
the Gigante, " Giant," of the Andes system on the opposite side of the deep
Canada depression.
The gneiss rocks of this sierra are distinguished from those of the Cordoba
system by their extreme richness in quartz and mica. East of Monigote a short
chain of volcanic heights, disposed transversely to the longitudinal axis, rises in
the Tomolasta to an altitude of 6,850 feet, culminating point of the plateau and
of the whole group. From its auriferous deposits this mountain has received the
name of Cerro de las Minas.
The Tandil and Ventana Heights.
Between the Parana and the Uruguay the surface is broken only by slight
rising grounds, or by fluvial cliffs ; but in the territory of the Missions, which
stretches eastwards into the Brazilian State of Santa Catharina, the campos
plains are traversed by a ridge with crests of from 1,000 to 1,300 feet.
Distinct chains also rise east of the Patagonian Andes in the province of
Buenos Ayres and in the southern territories. A first line of crests runs north-
west and south-east parallel with the Lower Parana, terminating at the head-
land of Cape Corrientes. In the Sierra de Tandil this system rises to a height
of 1,100 feet, and farther on in the direction of the south-east the Sierra del
Vulcan has an altitude of 930 feet. Like the other heights of the surrounding
region the Sierra del Vulcan consists of granites, gneiss, and archaic rocks. But
there are no recent lavas, as might be supposed from the name of the range. But
this term " Vulcan " is not a Spanish, but a local Indian word, which would