Definition of shelf

The word plateau is very common in geology and geography and to designate a flat surface (or a plain) located at an altitude (height) considerable compared to the sea level. These elevated surfaces can occur by the action of tectonic forces or by the erosion of the ground. In the first case, the forces exerted on the horizontality of the land are faults that are were at the origin of a rise. In the case of erosion, rivers are formed and deepen the field leaving some areas isolated and at a greater altitude.
It is worth mentioning that there are underwater plateaus the collapse or flooding (flooding) trays once emerged. We will quote as an example of submarine shelf Seychelles Islands, which occupy a territory separated from the continent by water.
Located at a higher altitude are the Tibetan Plateau (at over 4000 meters of altitude) and the Andean Altiplano (at more than 3000 meters of altitude). Regarding the surrounding terrain, the tepuys of the Venezuela, the Brazil and Guiana are plateaus the highest, vertical walls have more than 1 kilometer of altitude.
The term plateau may also designate a kind of dish on which we can serve tea or coffee, for example. At the theatre, the plateau is simply the scene.
Figuratively, it's a period without changing or even of stagnation: "the economy is on a tray, without major changes".