Sometimes they occupy the approaches to tablelands, the narrowest points of gorges, or the fords of rivers; sometimes almost inaccessible mountain tops or important points on ridges; and it may be noticed that, where two important nuraghi are not visible from one another, a small one is interpolated, showing that there was a system of signalling from one to another.
For purposes of surface description, Argentina may be divided primarily into three great divisions - the mountainous zone and tablelands of the west, extending the full length of the republic; the great plains of the east, extending from the Pilcomayo to the Rio Negro; and the desolate, arid steppes of Patagonia.
On the higher, arid, sun-parched tablelands of San Juan.
Per annum, the tablelands 32 in., and the western interior has an average as low as 20 in.
The climate of the Northern Territory is extremely hot, except on the elevated tablelands; altogether, the temperature of this part of the continent is very similar to that of northern Queensland, and the climate is not favourable to Europeans.
The flat lands which extend from the base of the Alpine foothills to the shores of the Arctic Ocean, assume the character either of dry deserts, as in the Aral-Caspian depression, or of low tablelands, as in central Russia and E.
Russia; the Valdai tablelands, where all the great rivers of Russia take their rise; the broad and gently sloping meridional belt of the Ural Mountains; and lastly the Taimyr, Tunguzka and Verkhoyansk ranges in Siberia, which, notwithstanding their sub-Arctic position, do not reach the snow-line.
The northern shore, along the Gulf of Aden, is backed by tablelands separated by the beds of mountain torrents - generally dry.
In the south the Cevennes separate the cold and barren tablelands v.
The Amazonian chapadao, which includes the remainder of the great Brazilian plateau west of the Sao Francisco and Parnahyba regions and which appears to be the continuation of these tablelands westward, is much the largest of these plateau divisions.
The largest of these and the only one of commercial value is the Ribeira de Iguape, which has its source on the tablelands of Parana and after receiving several affluents west of the Serra do Mar breaks through a depression in that range and discharges into the Atlantic"some miles below Santos on the southern boundary of the state of Sao Paulo.
The sun temperature is high on these barren tablelands, but the nights are cool and refreshing.
South and south-west of this arid plateau lie the inhabited tablelands of Rio de Janeiro, Sao Paulo and Minas Geraes, where the climate is greatly modified by a luxuriant vegetation and southerly winds, as well as by the elevation.
South of Sao Paulo the tablelands of Parana, Santa Catharina and Rio Grande do Sul enjoy a temperate climate, with an abundant rainfall.
Rising in the high tablelands or on the slopes of the Drakensberg or Lebombo mountains the rivers in their upper courses have a great slope and a high velocity.
The surface presents few striking topographic features, and may be subdivided into three vast plains or prairie tablelands rising one above the other from E.
Which may account, perhaps, for its rarity, if, indeed, it be really scarce in its native home, which is probably the eastern slopes and tablelands of the Bolivian and Peruvian foot-hills bordering on Brazil, inclusive of the headwaters of the Purus, Acre and Jurua rivers.
Of these rocks Sir Archibald Geikie says: " Two great phases or types of volcanic action during Carboniferous time may be recognized - (r) Plateaus, where the volcanic materials discharged copiously from many scattered openings now form broad tablelands or ranges of hills, sometimes many hundreds of square miles in extent and 1500 ft.
The process by which the ancient tablelands have been trenched into valleys and confluent ridges is most instructively displayed among the higher mountains, where erosion proceeds at an accelerated pace.
On the African side there are in the north wide stretches of desert plain, which towards the south rise to elevated tablelands, and ultimately to the mountains of Abyssinia.