intrusive extrusive

EXTRUSIVE FEATURES

1. These are formed by large outpourings of fluid lava from long narrow openings in the crust (fissures).

2. During each eruption the lava flows out from these openings, solidifies and builds a new layer each time forming layer upon layer of solidified basalt lava.

3. The plateau looks flat and featureless and often has little vegetation cover

WHAT ARE THEY?

1. Its in India

2. It is 700,000km squared in area.

3. It was formed by 29 lava flows from a hot spot which is now under Reunion Island in the Indian Ocean.

FACTS?

Other famous plateaus?

Columbia plateau in the USA and Antrim Plateau in Norther Ireland. Can you find out brief information about these too?

Loads of different volcano types.

Type depends on:

•Type of lava/ eruption

•Type of plate boundary

What are its characteristics and why?

CASE STUDY MAUNA LOA - HAWAII

What are their characteristics and why?

CASE STUDIES: MOUNT ST HELENS, MONTSERRAT

INTRUSIVE FEATURES

WHAT ARE THEY?

WHAT ARE THEY?

WHAT ARE THEY?

Isle of Arran Case studyIsle of Arran Case study

Northern Hills - Arran

WHAT FEATURE?

Kidonan Shore - Arran

WHAT FEATURE?

Drumadoon point - Arran

WHAT FEATURE?

SEISMIC IMPACTS

FAULTING• The outer part of the earth is cold so when it is

stressed it breaks easily if pushed quickly.• These breaks (caused by seismic activity) are

called FAULTS.• They tend to occur on the boundaries between

plates but sometimes in the middle of plates too.• Faulting occurs in the top 10 – 15km of the

earth’s crust.

NORMAL FAULTSNORMAL FAULTS

• Hanging wall moves down leaving a very steep fault plane. Usually caused by the plates moving apart (divergent)

• The result of this fault movement is a cliff like feature called a fault scarp. A number of these were found in the Sichuan province in China after the earthquake there.

REVERSE FAULTSREVERSE FAULTS

• These occur when the hanging wall moves upwards. The forces here are compressional (convergent boundaries)

• A number of these were found in the Sichuan province in China after the earthquake there.

•12th May 2008

•Collision boundary (Indo Australian and Eurasion)

•7.9 Richter scale.

•60,000 plus deaths

The San Andreas FaultThe San Andreas Fault

RIFT VALLEYS - East AfricaRIFT VALLEYS - East Africa