Volcanic Activity - Chapter 1.4 Flashcards
Volcanos are generally found where tectonic are pulled appart or in collision. Because the __ is under great pressure in the mantle, many eruptions are violent. The __ is often accompinied by ___, __, ___, ___ and __.
magma, ash, steam, rocks, gas, boiling mud.
The Mid-Atlantic Ridge runs north of south for the full ___ length of the Atlantic Ocean. It is so high in places that is it exposed above sea level. One such place is ___.
16,000 km, Iceland
A mid-ocean ridge is an underwater ___. It is formed where two plates ___. As the plates ___, molten magma rises up from the mantle and fills the gap between the plates.
mountain range, move apart, seperate
Most volcanic activity takes place along the margins or boundaries of plates. What can volcanic activity result?
earhquake, mountain and volcanic activity
Magma reaches the surface through a ___. It may erupt violently, blasting material into the sky.
vent
When magma reaches the surface, it is known as ___. ___ pours out of the ___ and flows down the side of the cone. It cools and hardens.
lava, lava, crater
Other materials may also come out during the eruption. Layers of materials build up to for a ___ mountain.
cone-shape
A volcano still erupting is ___.
active
A volcano that has been quiet for hundreds of years but may erupt again is ___
dormant
A volcano that has ) not erupted in recorded times (thousands of years is ___
extinct
Describe a negative impact of volcanic activity, referring in each case to an examply you have studied.
Large volcanic eruptions can cause death and the destruction of property.
Describe a positive impact of volcanic activity, referring in each case to an example you have studied.
Volcanic materials produce fertile soils. Ash and cinder are natural fertilizers as they are rich in minerals
___ is a volcanic rock that is so light that it can float in water. It is used as an abrasive.
Pumice
When volcanic ash is weathered it makes a ___
fertile soil
