REVIEW FOR CHAPTER 6 – VOLCANOES

Where can we find volcanoes on earth? Most volcanoes are found near subduction zones and mid-ocean ridges. This explains why the map of volcanoes on Earth matches so well the map of tectonic plates. On the other hand, some volcanoes are located in remote places like in the middle of the Pacific plate (Hawaii), thousands of kilometres away from the nearest plate boundary.subduction zones

Before lava reaches the surface, the molten material is called? magma

Main hazards from a quiet volcanic eruption is…. Lava flow

Sometimes rising magma is blocked by horizontal layers of rock. The magma forces the layer of rock to bend upward into a landform called Dome Mountain

Landforms From Lava and Ash Composite Volcanoes Composite Volcanoes have quiet eruptions that alternate with explosive eruptions, forming layers of lava and ash. Chapter 6 Volcanoes

Stages of Volcanic Activity Chapter 6 Volcanoes Extinct Extinct volcanoes are considered “dead” meaning that it is unlikely that they will erupt again

Stages of Volcanic Activity Chapter 6 Volcanoes Dormant Dormant volcanoes are considered “asleep” or “sleeping bears” meaning that they may become active in the future

Stages of Volcanic Activity Chapter 6 Volcanoes Active Active volcanoes are considered “live” meaning that it is erupting, or has shown signs that it may erupt in the near future

Magma Reaches Earth’s Surface Chapter 6 Volcanoes Pyroclastic flow Pyroclastic flow is an explosive eruption that includes hot gases, cinders (volcanic ash), and bombs (volcanic rocks).

Magma Reaches Earth’s Surface Chapter 6 Volcanoes Aa Aa is a very thick, slow moving lava. Aa contains high amounts of silica, which gives it it’s thickness. When aa hardens, it forms a rough surface consisting of jagged (sharp) lava chunks.

Magma Reaches Earth’s Surface Chapter 6 Volcanoes Pahoehoe Pahoehoe is a very thin, fast moving lava. Pahoehoe contains low amounts of silica, which gives it it’s thinness. When Pahoehoe hardens, it forms wrinkle and rope-like rock formations. Pahoehoe is hotter than Aa.

Magma Reaches Earth’s Surface magma chamber pipe vent When a volcano erupts, the force of the expanding gases pushes magma from the magma chamber through the pipe until it flows or explodes out of the vent. Chapter 6 Volcanoes

Landforms From Magma Sills Sills Chapter 6 Volcanoes

Landforms From Magma Dikes Dikes Chapter 6 Volcanoes

Landforms From Magma Volcanic Necks Volcanic Necks Chapter 6 Volcanoes

Landforms From Magma Batholiths Batholiths Chapter 6 Volcanoes

Landforms From Lava and Ash Calderas Calderas are formed when a magma chamber is emptied after an eruption and the volcano mountain collapses into the empty space creating a crater. Chapter 6 Volcanoes Crater Lake, Oregon

Landforms From Lava and Ash Lava Plateaus Lava Plateaus are formed from runny lava (pahoehoe) that cools in flat sheets of rock. Over time these layers form high plateaus. Chapter 6 Volcanoes Steamboat Rock, Washington

Landforms From Lava and Ash Cinder Cone Volcanoes Cinder Cone Volcanoes have explosive eruptions of ash, cinders, and bombs that form a cone-shaped hill. Chapter 6 Volcanoes Mount Etna, Italy

Landforms From Lava and Ash Shield Volcanoes Shield Volcanoes have quiet eruptions and have gentle slopes, which are not steep. Chapter 6 Volcanoes