hazards

Question 1

what are the main physical layers of the earth

Answer 1

lithosphere

asthenosphere

lower mantle

outer and inner core

Question 2

what is the crust mainly made up of

Answer 2

silicates

Question 3

what makes up the lithosphere

Answer 3

crust and solid mantle

Question 4

whats the mantle mainly made up of

Answer 4

silicates but contains magnesium and iron

Question 5

what is the core mainly made up of

Answer 5

metal

Question 6

what is isostasy

Answer 6

the rising and settling of a part of the earths lithosphere

Question 7

define what a plate is

Answer 7

a piece of the earths lithosphere that sits on top of the heavier asthenosphere

Question 8

describe basal drag

Answer 8

higher temps on earths core generates zones of hotter magma which upwell
cooler denser material sinks down creating a continuous circulatory motion

pulling crust apart by basal drag

Question 9

describe ridge push

Answer 9

fresh magma up wells at mid ocean ridges forming new young , ocean lithosphere pushing rock up and out

oceanic core cools and thickens and is pushed downhill with new magma emerging

Question 10

describe slab pull

Answer 10

when cold, dense plates sink into the mantle causing the whole thing to be forced down due to weight
due to gravity

Question 11

what is continental fit

Answer 11

idea that countries fit together

Question 12

what is continental drift

Answer 12

theory that suggests that the continents have moved

Question 13

how has similar rock types provided evidence for continental drift

Answer 13

rocks of same age and type displaying same formations discovered in Europe, North America and Africa

Question 14

how has mountains provided evidence for continental drift

Answer 14

old mountain belt refinance found between 450 to 400 million yrs ago

Appalachian mountain range found in US and Greenland

Question 15

how has glacial deposits proved evidence for continental drift

Answer 15

deposits formed during Permo-carboniferous era are found in Antartica, Africa, South America suggesting continents reassembled in the South Pole

glacial striations - scratches on bedrock made by rocks embedded in ice show direction of glacier suggest ice flowed from a single point

Question 16

what is palaeomagnetism and what impact do they have on proving plate tectonics

Answer 16

when lava erupts on ocean floor iron-rich minerals are aligned with magnetic field of earth, this cools recording earths polarity this resets every 400,000 years

bands of normal and reverse polarity are mirrored each side of mid Atlantic ridge suggesting new rock added each Side and width creates a pattern

Question 17

what impact does ocean surveys have on proving plate tectonics

Answer 17

they help provide a detailed picture of the ocean bottom

help geoscientists identify mountainous features where new plates form and deep ocean trenches descend

Question 18

what was noticed about the age of the sea floor to help prove plate tectonics

Answer 18

shown to be very young ages for rock locations close to ridges and old for ocean floors near continental masses. older rocks were cooler and denser

Question 19

explain what a mid Atlantic ridge is

Answer 19

where oceanic lithosphere is drawn apart

upwelling mantle lifts oceanic lithosphere upwards

Question 20

what is decompression melting

Answer 20

when pressure is released rock that was previously held as a solid due to pressure liquifies

Question 21

why do volcanoes form at divergent plate boundaries

Answer 21

much higher volumes of basaltic magma are produced forming an island such as island

Question 22

what kinds of volcanoes do we get at divergent plate boundaries

Answer 22

• sheild volcanoes

Question 23

what kind of eruptions do we get at divergent plate boundaries

Answer 23

• icelandic and Hawaiian

Question 24

what is a transform fault

Answer 24

where two ridges are broken up and slide past each other horizontally

Question 25

what is pillow lava

Answer 25

when lava enters water rapidly and its surface chills rapidly forming a flexible rind around molten interior