Volcanoes
A view of the cones and craters of extinct volcanoes near the Puy de Dome, Auvergne, central France
Basalt lava flow
The surface of a basalt lava flow, near Kilauea on the Big Island of Hawaii. This is the type of lava texture known as ropy lava or pahoehoe, formed when the…
Basalt lava flow 2
The surface of a basalt lava flow, near Kilauea on the Big Island of Hawaii. Here, the crust formed on the top of the flow has cracked and collapsed as molten…
Santorini volcano
This view, from a viewpoint above the town of Fira, looks out across the caldera, the huge collapsed crater, of the Santorini volcano, which was formed after…
Lavas and tuffs, Santorini
This view of the inside wall of the caldera (collapse crater) on the island of Thira, shows the layers of lava and tuff that make up the cone of the old…
Granite boulders
Granite weathers slowly, by chemical weathering. Bodies of granite commonly have only a few, widely-spaced fractures, so that a typical style of weathering…
Granite scenery
This shows a typical landscape formed out of granite in a dry climate. Smooth rounded slopes are scattered with large boulders. The granite weathers to a warm…
Granite (detail)
Granites are coarse-grained rocks, as a rule, having cooled slowly at some depth. Commonly they consist of two different sizes of crystals - larger feldspars…
Basic dyke, cutting granite
The dark rock is an intrusion of basic magma intruded up a rather irregular crack through paler granite. Lion's Head, Cape Town, South Africa
Inclusion of metamorphic rock in lava
It is quite common to find lumps of other rocks trapped inside bodies of igneous rock. These are called xenoliths (literally "foreign rocks"). They may be…
