Lesson 6-Features associated with plate movement

Question 1

Ocean ridge

Answer 1

• Occur along divergant plate boundaries
• Speed of spreading can effect the ridge
• MAR-2-5cm, slow and steep
• East Pacific Rise-10-25,quick and gentle

Question 2

Rift valley

Answer 2

• Occur when plates move apart
• Central block unsupported
• Crust will drop between two paralell faults
• African and Somali plates pulling apart

Question 3

Deep Sea Trench

Answer 3

Occurs at destructive plate boundaries where oceanic lithosphere is subducted beneath continental plate
-forms trench, depressed area which can be very deep
-common around Pacific Ring of Fire
-important scientifically given ranges of species
-Mariana Trench

Question 4

Island Arcs

Answer 4

• Plate subducts, some of partially melts and water is releasde into the mantle wedge casuing melt here which causes magma to rise to the surface
  -forming a chain of volcanoes in middle of ocean
  -Japan and the Aleatian Islands

Question 5

Young Fold Mountains

Answer 5

• Rivers carry sediment into the sea bed where its deposited into the geosyncline
• The sediment builds up and high pressure is applied to the bottom where sedimentary rock is formed
• Continental plates move towards each other due to convection currents, causes this rock to fold up into mountains
  -Himilayas, Indian and Eurasian plate

Question 6

Volcanoes Shield and Composite

Answer 6

• Shield volcanoes-formed from layers of lava. Eruptions are typically non-explosive. Shield volcanoes produce fast flowing basic (fluid) lava that can flow for many miles.
• Composite volcanoes- formed from layers of ash and acidic lava flows.
  -contain complex internal networks of lava flows which contain intrusive igneous features such as sills and dykes. The eruptions from these volcanoes may be a pyroclastic flow rather than a flow of lava.