Crustal thickness globe (updated)

thingiverse

**Update 11/2019**: Added a second version with correct crustal thickness and no space for magnets, boasting 50x vertical exaggeration. This globe of the earth's topography opens to reveal the base of the crust (moho), an excellent aid for teaching and outreach in geology and geophysics. The relief at the surface and on the base of the crust are at the same scale (50x vertical exaggeration), making it a fantastic tactile way to explore the structures beneath our feet. The earth's topography is controlled by the thickness of the crust, which is lighter than deeper mantle rocks. As a result, crust is buoyant and "floats" at the earth's surface. If you want to know more about this concept, just Google "isostasy". This means that most high places like mountains have roots, much like an iceberg. The topography we see at the surface is small compared to the amount beneath it. Notice how the thickest areas of the model are found in the Himalayas, where crust reaches 80 km thick, and beneath the high Andes. Correspondingly, deep oceans with low topography are associated with thin crust. There are two models uploaded here: * The first version is scaled correctly to crustal thickness but lacks space for magnets, so it doesn't have a closing mechanism. It also has a small contact area with the print bed, which may cause adhesion issues and requires printing with a raft. * The second version is designed to be printed with embedded 5x2mm neodymium magnets by inserting gcode to pause the print and allow the magnets to be inserted at the correct layer. (Note for teachers/geeks/pedants: This crustal thickness is not to scale; surface relief and relief of the base of crust are at the same scale, but additional constant thickness was added to make it 3D printable and have space for magnets about 3.5 mm at 100% scale.) **Source data:** * Topography: ETOPO1 (https://www.ngdc.noaa.gov/mgg/global/) * Moho depth: CRUST1.0 (https://igppweb.ucsd.edu/~gabi/crust1.html)