CH 6 Prentice Hall p CH 6 Prentice Hall p Volcanic Landforms

Shield Volcano A wide, gently sloping mountain. – Lava pours out in thin layers and harden on top of older layers. – Viscosity= Low

Cinder Cone A steep, cone-shaped hill or mountiain. – If lava is thick and stiff it may produce ash, cinders and bombs. – Paricutin in Mexico (farmers field 400m high) – Viscosity = High

Composite Volcano A tall, cone-shaped volcano which alternates eruptions of lava flows with explosive eruptions of ash, cinder and bombs. Viscosity= High/Low Examples: – Mt. St Helens – Mt. Fuji in Japan

Lava Plateau Eruptions form high, level areas by flowing from several long cracks in an area. Thin runny lava travels far before cooling and solidifying. The flooding process repeats again and again building up high plateaus over millions of years. – Columbia Plateau (Washington, Oregon, & Idaho)

Caldera A huge hole formed from an enormous eruption that empties the main vent and magma chamber beneath the volcano. The hollow mountain then collapses inward due to lack of support. Fills with pieces of the volcano, ash and lava. – Crater Lake in Oregon

Soils from Lava & Ash Ash releases potassium, phosphorus and other materials that plants need. Soil develops and plants are able to grow. The richest and most fertile soils.

Volcanic Neck Forms from when magma hardens in a volcano’s pipe. – The softer rock wears away, exposing the hard rock. (weathering and erosion)

Sill Magma that squeezes and hardens between layers of rock. – (Horizontal like a window sill B in the diagram)

Dike Magma that forces itself across rock layers and hardens. – (Vertical, cuts through rock layers C in the diagram)

Batholith Large rock masses form that form the core of many mountain ranges. Formed when a large body of magma cools inside the crust. – D in the diagram

Dome Mountain Formed by smaller bodies of magma, when rising magma is blocked by horizontal layers of rock. – Forces rock layers to bend upward into a dome shape. – Rock layers above eventually erodes and leave the core exposed.