Rocks are classified into three main groups: igneous (rocks formed from the cooling of magma and/or lava), sedimentary (rocks formed from sediment grains which have been transported, deposited, and then cemented together), and metamorphic (preexisting rocks that have been changed by combinations of heat and pressure generated by deep burial, tectonics, hydrothermal processes, etc).
(Rocks; are classified; into three main groups) (sediment grains; cemented together; T:then) (rocks; formed; from the cooling of magma and/or lava) (rocks; formed; from sediment grains) (preexisting rocks; have been changed; by combinations of heat and pressure) (sediment grains; have been transported; ) (heat and pressure; generated; by deep burial, tectonics, hydrothermal processes, etc)
Rocks sediment grains rocks rocks preexisting rocks sediment grains heat and pressure
are classified cemented together formed formed have been changed have been transported generated
into three main groups
T:then
from the cooling of magma and/or lava
from sediment grains
by combinations of heat and pressure
by deep burial, tectonics, hydrothermal processes, etc