376 Miscellanies. 
This salt has claims of scientific interest quite equal to those of 
any mineral hitherto discovered. It indicates to us, who are accus- 
tomed toa humid climate, with heavy rain storms, a state of atmos- 
pheric dryness, as far removed from our experience as the singular 
products there deposited are from our own rocks and soils. 
During the scientific tour of Mr. John H. Blake, of Boston, a great 
number of specimens, illustrating the forms and composition of this 
salt, were collected, and I have been able to learn some facts from 
the chemical examination of them, but have to regret that the loss of 
Mr. Blake’s journal has prevented our having a full account of their 
geological relations. 
The Nitrate of Soda exists in large beds, a few feet below the sa- 
line soil, or forming that soil in various places, from Arica on the 
north and west, to the course of the river Loa on the south. The 
country is an elevated pampa, having the form of a shallow basin, 
bounded by the coast cliffs on the west, by the higher pampas on the 
north, by sandstone hills on the east, and the ravine through which 
the river Loa falls into the sea ou the south. The elevation of the 
pampa of Tamarugal in the province of Tarapaca is nearly 3300 feet 
above the level of ‘the Pacific. 
The western border or coast presents granite, on which the pale 
flesh-colored feldspar porphyry, peculiar to voleanic regions, reposes. 
This rock is doubtless trachyte, and its extent and volcanic character 
make it one of the most important of known rocks. Imbedded in the 
soil and forming extensive tracts, are shells of the same species as 
those now existing in the ocean. A saline soil and other appearances 
denote that a long line of coast has been elevated from below the 
ocean’s waters. In travelling north, Mr. Blake found that the pam- 
pas were broken by ravines, through which the waters from the Cor- 
dilleras flow at times. A remarkable feature is disclosed by these 
ravines: a section always presents a higher level on the north than on 
the south side, so that each pampa presents a steppe, rising as we ad- 
vance northward. The sandstone bills forming the eastern boundary 
re of moderate elevation; they contain beds of gypsum, and form 
oe western barrier of another basin, the eastern bounds of which 
are the Cordilleras. 
The pampa is mostly uninhabitable, but spots where water can be 
obtained, and parts of the ravines are cultivated. Nearly midway 
between the eastern and western limits of this pampa there exists a 
buried forest of large trees, mostly of the Algorabo species. The 
trees are inclined towards the southwest, and the wood is singularly 
reserved. Specimens have the color and grain of old mahoga- 
re brittle. The gaseous constituents of recent wood seem 
* 
