Geologically, Suriname onshore is subdivided into a crystalline basement (80%), and a coastal plain (20%).
The crystalline basement forms part of the Guiana Shield, which stretches between the Orinoco and the Amazon rivers and includes eastern Venezuela, Guyana, Suriname, French Guiana, and northern Brazil. The crystalline basement is formed principally of igneous and metamorphic rocks, whilst the coastal plain, which stretches along the northern fringe of the shield area, is exclusively sedimentary.
The offshore extension of the coastal plain is a large sedimentary basin that was formed in the Jurassic and is filled with clastic and carbonate sediments.