Shield (geology)

This article is about the large-scale geological regions. For the volcano type, see shield volcano.
Geologic provinces of the world (USGS)

A shield is a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas.[1] These rocks are older than 570 million years and sometimes date back to around 2 to 3.5 billion years.[citation needed] They have been little affected by tectonic events following the end of the Precambrian, and are relatively flat regions where mountain building, faulting, and other tectonic processes are minor, compared with the activity at their margins and between tectonic plates. Shields occur on all continents.

  1. ^ Kearey, P. (2001). The new Penguin dictionary of geology (2nd ed.). London: Penguin. p. 243. ISBN 0-14-051494-5. OCLC 59494925.