Introduction to Igneous Rocks

Why does oceanic plate sub-duct underneath the continental plate (check all that apply)

• It is pushed by a mantle rock spreading along the mid-ocean ridge

• It is dragged downward because it contains minerals that are less dense than continental rock

• It is dragged downward because it contains minerals that are more dense than continental rock

• It partially remelts to form felsic minerals

Earthquakes occur along the west coast when ____

• The Pacific Plate slips along east-west fault lines with the Juan De Fuca Plate

• Cascade Volcanic Arc periodically erupts overtime

• The Juan De Fuca Plate breaks as it is subducted under the North American Plate

• When magma solidifies into rock

The mantel is ____

• solid and rigid

• molten and plastic

• cold and liquid

• gaseous

Deep oceanic rock that is dark, coarse grained and dense is known as ______

• Granite

• Basalt

• Gabbro

• Andesite

Basalt lava that flows into the ocean is are quenched by cold seawater and forms ____

• Obsidian

• Gabbro

• Scoria

• Granite

Which mineral would not be likely found in a felsic rock? ____

• Olivine

• Quartz

• Mica

• Potassium Feldspar

This rock would be classified as a _________

• Basalt

• Gabbro

• Rhyolite

• Granite

This vesicular rock would be classified as _______

• Obsidian

• Granite

• Scoria

• Rhyolite

The three (3) types of volcanoes are ____ (mark all that apply)

• Composite

• Shield

• Fissure

• Cinder

Mount Mauna Loa has a height of _____ from its base to its peak.

• 29,000 feet

• 29,0000 meters

• 56,000 feet

• 24,000 feet