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Marli Bryant Miller: www.marlimillerphoto.com

Contact Metamorphism (often called thermal metamorphism) happens when rock is heated up by an intrusion of hot magma.

In this photo, the dark grey rock is an intrusion (a sill) between layers of a paler grey limestone. Just above and below the intrusion, the limestone has been altered to form white marble.

Contact Metamorphism can occur on scales from a few millimetres either side of a small intrusion, to several hundred metres around a large igneous body such as a batholith.

There may be several zones where different metamorphic effects can be seen, depending on how hot the rock became (left).

Contact Metamorphism does not involve squashing of rock layers, so these rocks do not have foliated textures like regionally metamorphosed rocks.