1911 Encyclopædia Britannica, Volume 9… (1911)
“ On the south the comparatively low range of the Sierra Morena constitutes the frontier of Andalusia; on the east and west there is a still more gradual transition to the plateau of New Castile and the central plains of Portugal. The tableland of Spanish Estremadura is itself bisected from east to west by a line of mountains, the Sierras of San Pedro, Montanchez and Guadalupe (4000–6000 ft.) , which separate its northern half, drained by the river Tagus, from its southern half, drained by the Guadiana. ”
