IMPACT ON THE landscape FROM TECTONIC ACTIVITY.

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.

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.

A Batholith is a formation of magma that has cooled relatively close to the surface of the Earth’s 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

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 Earth’s surface and then intruded into overlaying sedimentary/metamorphic host rock. Sills are concordant structures.

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.

Formation and types Plate Boundaries vs hot spots

Composite volcanoes Steep sided Pyroclastic (explosive) eruptions A huge threat when they erupt Typically found on destructive boundaries Mount Fuji, Japan is an example.

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

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

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

Hotspots Areas prone to tectonic hazards. The Philippines Eurasian boundary and California's San Andreas boundary are examples of a hotspot. magnitude-earthquake-felt-mindoro- philippines-june-25/

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

Rift Valleys Iceland Rift Valley Jordan Rift Valley Olduvai Gorge, in Tanzania's Great Rift Valley

Faults Normal fault Reverse Fault

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

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

Extrusive igneous activity Activity of Magma or Lava on the earth’s crust Most typical example is lava flows, which can be over 1,250°C 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 profile.html?source=sem_G2308&gclid=CNrRy-rM75gCFQrAGgodm1Fh1w

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.

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.