Download Major Rock Categories

Atlas of Canada 6th Edition
(archival version)
Major Rock Categories
Rocks are divided into three main categories according to how they were formed: igneous, sedimentary or
metamorphic processes. Rocks differ in their texture, mineral and chemical composition, and bedding characteristics depending on which of these three processes that formed them. Igneous rocks, which are also
referred to as magmatic rocks, are formed from materials that come from the depths of the Earth. There are
two categories of igneous rocks: intrusive (or plutonic) rocks and volcanic rocks. Sedimentary rocks are the
product of the consolidation of loose sediment that has accumulated in beds. A metamorphic rock is derived
from a pre-existing igneous or sedimentary rock that is transformed, to a greater or lesser degree, by the
action of physical factors such as temperature and pressure, or chemical factors that include the addition of
new minerals.
Lambert Conformal Conic Projection. Standard Parallels 49°N and 77°N
Source(s):
Major Rock Categories
Geological Map of Canada - Map D1860A [CD-ROM]. 1997. Ottawa, Ontario: Geological Survey of Canada,
Natural Resources Canada.
© 2009. Her Majesty the Queen in Right of Canada. Natural Resources Canada.
This product was originally published as an interactive map in the online Atlas of Canada, 6th Edition. It
was not intended for high resolution reproduction and therefore does not conform to the standards of
cartographic representation and map design found on the Atlas of Canada’s paper reference maps.