Guiana Shield - Geomorphology

Geomorphology

There are three upland areas of the Guiana Shield:

1. The Guiana Highlands proper are in Venezuela east of the Orinoco and extend across much of west-central Guyana and into the northern Roraima state in Brazil.
2. The Tumucumaque Uplands which are a series of central massifs in an arc from the Wilhelmina Mountains of south-central Suriname, along the southern boundary of Suriname and Guyana, forming the Acarai Mountains of Roraima state and the Tumuc-Humac Mountains of Pará and Amapá states of Brazil. From this arc, the southern uplands slope gently downwards towards the Amazon River and the northern uplands slope gently downwards toward the Atlantic.
3. The Chiribiquete Plateau is a sandstone topped plateau with an elevation of 900 m (2,953 ft) that forms the western edge of the shield. The plateau is separated from the eastern Andes by the thick Neogene sediments of the Sub-Andean Trough that runs along the northern and western rim of the Guiana Shield.

The north-central part of the Guiana Highlands is dominated by high flat-topped peaks called tepuis, of the Roraima supergroup and Quasi-Roraima formation, and the rounded granite peaks of the Parguaza and Imataca complexes to the north and southwestern edges of the area. The highest point in the shield is Pico da Neblina in Brazil (next to the Venezuelan border) at 2,994 m (9,822 ft). Pico da Neblina is the highest summit of the larger Neblina massif, a highly eroded sandstone plateau that straddles de Venezuelan-Brasil border and that has lost the typical tabletop shape of the other tepuis in the region.