Definition: Open shrubland and savanna in the north of Brazil and in Colombia and Venezuela, with low, sparse vegetation growing on sandy soils mostly within terra firme land in the Amazon. It can be of the ‘forested’ type, similar to a gallery forest, ‘wooded’ where the trees are shorter, and finally ‘grassy-woody’, where it occurs in wet plains near rivers and lakes. Amongst the more frequent plant families are the Arecaceae, Bromeliaceae, Clusiaceae, Humiriaceae, Marantaceae, Meliaceae and Rapateaceae.
Definition: A group of hydrous aluminium phyllosilicate (phyllosilicates being a subgroup of silicate minerals) minerals (see clay minerals), that are typically less than 2micrometres in diameter. Clay consists of a variety of phyllosilicate minerals rich in silicon and aluminium oxides and hydroxides which include variable amounts of structural water.
Definition: A depression caused by erosion by water or ice. Low-lying land bordered by higher ground; especially elongate, relatively large gently sloping depressions of the Earth's surface, commonly situated between two mountains or between ranges of hills or mountains, and often containing a stream with an outlet.
Definition: A section of the Earths's crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its internal structure while being displaced as a whole.
