_ Description of the Landes of Acquitania. ae 
line the coast, constituting the back ground of the pine forests, 
and of the plains of green heather. No small addition to the beau- 
ty of the latter, is derived from the predominance of a heath, (Erica 
ciliaris,) one of the prettiest among European species. Green is a 
colour at all times pleasing to the eye ; that of this plant is pecu- 
liary so, and its delicate leaves and graceful form, waving in the 
winds, or breaking the intensity of the sun’s rays, give at once an 
agreeable relief to the eye, and excite the traveller’s admiration. 
In the west of the old world, there are now few uncultivated 
tracts, and those which do occur have generally much similarity of 
formation ; the deposits and unconnected debris of which the heaths 
and moors of Germany, France, and England, and the elevated 
plains of the Iberic peninsula, known by the name of Parimas, con- 
sist, have, from their supposed origin, been denominated upper ma- 
rine, and placed among the latest geological epochs, as appertaining 
to the last catastrophes which may have operated on the earth’s 
surface. Some deposits are of a different nature, as the “ Bruyeres,” 
near St. Omer, and the downs of Maestricht. The boulder masses 
which occur disseminated over the great plains of Germany and 
Holland have been supposed to have descended from the north. 
America, so lately under the control of civilization, contains many 
barren and uncultivated tracts; among these, the Havannahs, Llanos, 
Pampos, and Campos, stand predominant : the Prairies occur gene- 
rally on calcareous formations, and are often traversed by subter- 
ranean rivers. In the old world occur many waste tracts of modern 
formations. The steps * between the Caspian and Black Seas are of 
recent date; the theory of their origin, first advanced by Tourne- 
fort has since been developed by Pallas, Lamouroux, and other late 
writers ; but the surface of the uplands of Tartary, supposed by 
Barrow to be nearly 10,000 feet (3000 metres, Cordier) above the 
level of the sea, the moving sands of the Shamo, and the deserts in 
the interior of Africa, very probably date as far back as the oldest 
rocks of the supermedial order, (new red sandstone, with gypsum 
and saliferous deposits ?) 
The existence of uncultivated tracts is, wherever they occur, 
closely related as well to the geognosy as to the hydrography of the 
land ; and while the climate will influence the nature of the vege- 
tation, still these tracts alone present that vast continuity of the 
‘same plants, which afford the best characters for their recognition, 
and are of so much service in developing the physical distribution 
of the vegetable kingdom. om 
With respect to its geognostic constitution, the tract of land com- 
prising the vast basin extending from Thoulouse to Narbonne, sepa- 
rating the Pyrenees from the Montagne Noire, and through which 
runs the great canal of Languedoc, the undulating and champaign 
country at the head of the rivers Garonne and Adour, the extensive 
and fertile plains of Gascony, and the uncultivated Landes, are all 
* Step, and not steppe, (as the Germans, British, and French generally spell 
it,) on the authority of Dr. Lyall. (Travels in Russia, &c. Note, p. 134.) 
