_El Llano Estacado._--A typical portion of the great plateau region left by deep dissection is furnished by the table-land named by early Mexican explorers "El Llano Estacado," or the Staked Plains, in reference to the fact that owing to the monotony of the surface and the scarcity of water the routes of travel were at first marked by stakes. This region, celebrated in the traditions of the Southwest frontier, is described by Captain Marcy, who crossed its eastern portion in 1849, as being "much elevated above the surrounding country, very smooth and level, and spreading out in every direction as far as the eye can penetrate, without a tree, shrub, or any other herbage to intercept the vision. The traveller in passing over it sees nothing but one dreary and monotonous plain of barren solitude. It is an ocean of desert prairie, where the voice of man is seldom heard, and where no living being permanently resides. The almost total absence of water causes all animals to shun it; even the Indians do not venture to cross it, except at two or three points, where they find a few small pools of water." As will be shown below, the barrenness and desolation of this arid tract is not so great as it seemed to those who first invaded its primeval solitude. El Llano Estacado, or the _Llano_, as it is frequently termed, is about 500 miles across from north to south, and 280 miles wide from east to west. It is bordered on nearly all portions of its periphery by descending escarpments which lead down to the adjacent valleys. Its surface, although appearing horizontal, in reality slopes eastward at the rate of about 20 feet per mile, and on its highest, northwest border, has an elevation of 5,500 feet above the sea. This great table-land has a smooth floor, and, as reported by recent explorers, is clothed with an abundance of bunch-grass, which formerly furnished sustenance to herds of antelope and deer. It was in this general region also that some of the immense herds of buffalo which once inhabited the broad plateaus found a winter range.