Earth's crust

Isopach map showing thickness of the Earth's crust in km.

Map source: Map of Crustal Thickness
USGS

Map documented in:
W.D. Mooney, G. Laske and G. Masters, 1998. CRUST 5.1: A global crustal model at 57°x5°. J. Geophys. Res., 103, 727-747.

Questions for thought

How does an isopach map differ from a contour map?
Is the thickness of the crust related to land or ocean?
Where is the crust thicker - under land or oceans?
How thick is the crust 1) under land and 2) under oceans in units of kilometers and miles?
How do scientists know the depth to the bottom of the crust?
What is the Moho or "Mohorovic discontinuity"?

Related resources

Crust 2.0: A New Global Crustal Model at 2x2 Degrees
Explains how crustal thickness was determined. A newer model than Crust 5.1.
Bassin, C., Laske, G. and Masters, G., The Current Limits of Resolution for Surface Wave Tomography in North America, EOS Trans AGU, 81, F897, 2000.
Crust 5.1: A New Global Crustal Model at 5x5 Degrees
Explains how crustal thickness was determined.
W.D. Mooney, G. Laske and G. Masters, 1998. CRUST 5.1: A global crustal model at 5�x5�. J. Geophys. Res., 103, 727-747.