GEO week 2: Rock Cycle

What is a rock?

Coherent, naturally occurring solid, consisting of minerals or, less common, a mass of glass

Rock grain

any fragment or piece of mineral, rock, or glass

Clastic

rocks whose grains are stuck together by cement

cement

mineral material that precipitates from water and fills the empty space between grains

crystalline

rocks whose crystals interlock with one another like piece in a jigsaw puzzle

the crystal penetrates each other

for example, this is what holds granite together!

igneous rocks

form by solidification of molten rock

rock forming process of crystallization

formed along ocean ridge axis and above subduction zones

sedimentary rock

form either by cementing of fragments (grains) together or by the precipitation of mineral crystals out of water solutions (near Earth surface)

• weathering and erosion of rocks exposed at surface

• rock forming process: deposition, burial, and lithification

form between the oceanic lithosphere and continental lithosphere

metamorphic rock

form when preexisting rocks change in character in response to a change in pressure and temperature conditions, and/or as a result of squashing, stretching, or shear

• change happens in the solid rock state so no melting required!

• rock forming process: recrystallization in solid state of ne

these rocks are found by continent and mountain belts and at collision zones (where two continental lithospheres collide)

grain size

dimensions of individual grains in a rock (fine or course)

equant and inequant rocks

if the minerals grain in rock have the same dimensions in all directions or they do not

composition

proportions of different chemicals, and thus minerals, making up the rock

texture

arrangement of grains in a rock, that is, the way the grains connect to each other and whether they are inequant grains aligned with each other

layering

defined by bands of different compositions or textures, or by the alignment of inequant grains (aka rock minerals laying atop each other, like a lasagna)

mass transfer cycle

transfer or movement of materials to different parts of the Earth system

basically the movement from igneous → sedimentary → metaphoric, and then back again