Geology. 125 
of interesting details and conclusions. The observations on which the 
results immediately depend were extended over a triangular space, the 
vation of it above t is probably about 600 mete ther 
tertiary plain of equal extent is that of the basin of the Duero, situated 
to the north a little to the westward, and separated from th r by 
and Sepulveda, and the city of Valladolid at its center. Cretaceous 
deposits enclose it on three sides, and metamorphic rocks, gneiss and 
granitic, on the other or Portugal side. Its mean height is over 700 
meters. 
The tertiary deposits of these two great basins are similar throughout. 
ey are evidently lacustrine in origin, and consist of a superior cal- 
and in th 
from Valladolid. In two mountains called Las Tetas de Viana, the 
tertiary rocks reach a height of 1070 meters. . 
The great height of these two tertiary basins above the sea is re- 
markable. There are other basins but they are lower, such as the 
basin of the Ebro, which is four or five hundred meters below those 
tion—and recalls involuntarily, the authors state, the Atlantis of Plato, 
or the opinion, more scientific, of Mr. E. Forbes, that Ireland and Spain, 
if not united, were so near one another that the former received from 
