Intrusion is the movement of magma from underground into spaces
in the rock strata, once this magma has cooled and solidified an
intrusive landform has been created, events such as weathering an
erosion causes the landform to become exposed. There are several
types of these formations, for example: Batholiths, Sills and Dykes
are all intrusive formations.
Slide 3
Two main types of Igneous Intrusions. In a formation there is
one of two main features that it can have. It can either be
concordant or discordant. If a formation is concordant that means
that it is parallel to the bedding planes. Whereas a discordant
formation means that it is across the bedding planes.
Slide 4
A Batholith is a formation of magma that has cooled relatively
close to the surface of the Earths crust. They are underground
masses of magma that often form dome-like chambers. Batholiths are
also large bodies, and the largest type of pluton, a batholith must
cover at least 100km2 to be identified as a batholith, though many
are much larger. Cornubian batholith, UK. Batholiths are discordant
structures
Slide 5
A sill is a formation of igneous rock. Despite being formed
underground Sills can eventually become exposed. They are composed
of plutonic igneous rocks. They are formed from magma that has
solidified beneath the Earths surface and then intruded into
overlaying sedimentary/metamorphic host rock. Sills are concordant
structures.
Slide 6
A Dyke is, in some ways, similar to a Sill in the way that it
pushes through already present rock, although a Dyke pushes its way
through vertically rather than horizontal like a Sill. There are
two types of Dykes: Sediment and Magmatic. Sediment Dykes: Form
when cracks in host rocks are formed and sediment fall into them,
thus creating a dyke. Magmatic Dykes: formed with the cooling of
magma leaving a formation that is forcing its way upwards.
Slide 7
Formation and types Plate Boundaries vs hot spots
Slide 8
Composite volcanoes Steep sided Pyroclastic (explosive)
eruptions A huge threat when they erupt Typically found on
destructive boundaries Mount Fuji, Japan is an example.
www.geography.learnontheinternet.co.uk
Slide 9
Shield Volcanoes Gentle slopes caused by layers of lava Produce
fast flowing lava Frequent eruptions Destroy property but rarely
harm people. Found on constructive boundaries Mauna loa, Hawaii is
an example www.geography.learnontheinternet.co.uk
http://volcano.oregonstate.edu/definitions/shield-volcano
Slide 10
Dome Volcanoes (Acid lava cones) Lava is thicker than standard
lava Very steep sided as a result of this lava Not explosive/a
threat Mount St. Helens is an example
http://volcano.oregonstate.edu/lava-domes
Slide 11
Plate boundaries Plate boundaries are: Convergent, divergent
and transform. Convergent; two plates coming together creating a
rugged mountain range and a seafloor trench. Divergent; two plates
moving away from eachother, magma flows out and hardens into solid
rock on the crust. Transform; where two plates slide past one
another, Most transform faults are found in the ocean basin
www.oceanexplorer.naa.gov
Slide 12
Hotspots Areas prone to tectonic hazards. The Philippines
Eurasian boundary and California's San Andreas boundary are
examples of a hotspot. http://pinoyambisyoso.com/news/5-6-
magnitude-earthquake-felt-mindoro- philippines-june-25/
Slide 13
The impact on landscapes depends on a number of factors such as
the magnitude and scale of the event and the types of material
being extruded
Slide 14
Rift Valleys Iceland Rift Valley Jordan Rift Valley Olduvai
Gorge, in Tanzania's Great Rift Valley
Slide 15
Faults Normal fault Reverse Fault
Slide 16
Microfracturing/microseismicity Small-scale failures on an area
the size of a dinner plate Releases stress under high-strain
conditions When sufficient microfractures link up to a large slip
surface a serious seismic event or earthquake can occur
Slide 17
Liquefaction Tilted apartment buildings at Kawagishi cho,
Niigata, Japan; the soils beneath these buildings liquefied during
an earthquake in 1964 Liquefaction also occurred as a result of the
earthquake in Haiti in 2010 and caused 30 deaths
Slide 18
Extrusive igneous activity Activity of Magma or Lava on the
earths crust Most typical example is lava flows, which can be over
1,250C Can also lead to lava bombs Boulders of lava which rain down
on the landscape, very destructive Longer term effects include the
generation of physical structures, of which there are three main
types: 1.Volcanic Cones 2.Volcanic Fissures 3.Lava Plateau
http://environment.nationalgeographic.co.uk/environment/natural-disasters/volcano-
profile.html?source=sem_G2308&gclid=CNrRy-rM75gCFQrAGgodm1Fh1w
Slide 19
LAVA PLATEAU Shield volcanoes may erupt along lines of fissures
rather than a central vent spilling liquid lava in successive
layers. Over time as these layers form broad plateaus such as the
Columbia Plateau. These plateaus are often cut by deep canyons that
expose the layers of rock.
http://www.livescience.com/27295-volcanoes.html
Slide 20
VOLCANIC FISSURES Linear volcanic vent, that allows lava to
flow through. It is not usually linked to explosive activity, can
be a few metres wide and varies in length.