igneous rocks🌋🔥🌄

fire???? like pyro???? like tf2 pyro???

igneous rocks

the products of the cooling + solidification of magma/lava.

composition → silicic, intermediate, mafic + ultramafic

crystal grain size → coarse (>5mm) medium (1-5mm) fine (<1mm)

evidence for depth of formation, rate of cooling + cooling history of igneous rocks

crystal grain size, crystal shape + texture

some crystal shapes

• euhedral → flat faces with sharp angles.

• subhedral → incompletely bounded by crystal planes: partly faced.

• anhedral → a mineral that shows no crystal habit.

some crystal textures

• equicrystalline

• porphyritic

• vesicular

• glassy

• fragmental (tuff)

• amygdaloidal

• flow banding

some crystal surfaces

• pillow structure

• aa

• pahoehoe

• columnar joints

evidence for the earth’s internal heat

• increased temperatures in mines & boreholes

• hot springs

• volcanoes

• satellite imagery + remote sensing to measure surface temperatures → measuring the change in surface temperature is one way of predicting volcanic events

• at the base of some glaciers, the ice melts due to heat coming up from the crust = easier to move

mines + boreholes

Kola Superdeep Borehole in Russia → at a depth of over 12 000 metres, the rock became too plastic to drill through, at a higher than expected temperature of 300C

hot springs

where magma lies close to the surface, percolating groundwater becomes heated + rises to the surface by hot natural