pg.+537+and+pg.+538

=​ Pg. 537 =  b) Rift eruptions c) Shield volcano =Pg. 538 =
 * 15.** a) Composite volcano

**12.** Continental drift theory b) Volcanic island arc c) Lithosphere d) Oceanic crust e) Asthenosphere 
 * 13.** A - convergent, B - divergent, C - transform
 * 14.** Neither of these plate boundaries involve subduction - the action of one plate pushing below another - which causes volcanoes to erupt. In continental-continental plate boundaries, the plates have similar densities, therefore, when they collide, they form mountains, such as the Himalayas. In transform plate boundaries, the plates just slide past each other.
 * 15.** Mountain ranges that begin on one continent end at the coastline and appear to continue with similar charactaristics - composition and size - on a continent across the ocean. This proves that these continents were once joined.
 * 16.** If mantle convection stopped, the continents would no longer move because these currents move the tectonic plates which move the continents. Also, the formation of mountains and ocean basins, volcanoes, and earthquakes, would no longer occur because there would be no movement between the tectonic plates.
 * 17.** The magma (lava) and rocks that come from volcanoes come from Earth's interior, allowing geologists to study the composition of Earth's interior.
 * 18.** They occur near plate boundaries because when two plate boundaries move apart, molten rock - lava - rises up and creates volcanoes. Also, sometimes, when two plates collide and result in a subduction, the friction between the two plates makes one of them melt resulting in lava rising up, and once again, creating a volcano.
 * 19.** Rift eruptions would affect the forests and ecosystems of BC badly because of the large amounts of lava released.
 * 20.** Many earthquakes are too small to detect. They happen without us even knowing. Other ones are hard to study because they involve a unique set of forces and geological structures, making it very difficult to accurately predict the timing, size, and location. Alos, the event leading up to an earthquake occur over a time perdiod of more than a human lifespan.
 * 21.** a) Trench