Three kinds of rock are under your feet
How do they form and rearrange?
Igneous from liquid, sedimentary from grains,
Metamorphic from the mighty heat & pressure change!
Rocks are a-changin' all of the time
Rocks keep a-movin' - low to high to low
The rock cycle forms all the land that we know
But you hardly ever see it cause it goes.....real......slow.
Hot molten rock lies deep underground
Magma building pressure for a volcano
It might form big crystals called intrusive igneous
But you can't take that for granite, you know!
Sometimes the pressure makes it blow that top
And magma turns to lava comin' up through the crust
Tiny crystals form as it cools off fast
Obsidian and basalt -- extrusive igneous!
Weathering, erosion, and chemical change
Breaks and washes rock down into sediment
Layers of pebbles, silt, and sandy grains
We say deposition is the name of this event
Sandstone, mudstone, limestone and shale
Compression, cementation and the ticking clock
Will take loose grains like dirt in a pail
And glue it into sedimentary rock!
Now if a rock is buried miles underground
That rock can undergo a metamorphic change
The heat and the pressure are squeezing all around
The crystals reform and layers rearrange
Shale turns to slate, limestone to marble
Rocks metamorph into different types
All those neat layers get squeezed up and garbled
But foliated rock still has zig zaggy stripes