the.com/crustal structure
earth's outer shell, layered like a lie you keep adding detail to.
means the arrangement, thickness, and composition of the rocky layers that make up the planet's crust, mapped mostly by watching how seismic waves bend through it.
from the term crystallized in early 20th-century seismology, after andrija mohorovicic noticed earthquake waves changed speed at a sharp boundary in 1909, revealing the crust had a bottom.
oceanic vs continentaloceanic crust is thinner, denser, younger everywhere
discovery methodfound entirely by listening to earthquakes
thickness range5 km under oceans, 70 km under mountains
constant recyclingoceanic crust rarely survives past 200 million years