FAQ: Geological Puzzles Made Clearer
Short, careful answers to the questions we hear most. Each one points to the process involved, and to the page where it is explained more fully.
Processes and Time
Are rock formations still changing?
Yes. Weathering and erosion continue everywhere. Arches collapse, hoodoos lose their caps and coastlines retreat — usually too slowly to notice, occasionally all at once, as when Wall Arch fell in 2008. Arches
What is the difference between weathering and erosion?
Weathering breaks rock down in place, by frost, chemistry or roots. Erosion carries the pieces away by water, wind, ice or gravity. Most landforms involve both.
How do geologists know how old a formation is?
They combine the order of layers (younger usually on top), fossils, and radiometric dating, which measures the steady decay of radioactive elements in minerals. Speleothems are often dated with uranium–thorium methods.
Specific Wonders
Why are basalt columns often hexagonal?
Cooling lava contracts and cracks. Cracks growing inward settle into a pattern that releases stress efficiently, which tends toward six sides, though five- and seven-sided columns are common. Columns from cooling
Is the Giant's Causeway man-made?
No. The legend of Finn McCool is part of its cultural story, but the columns formed naturally as thick basalt flows cooled around 50 to 60 million years ago.
How did the crystals in Naica grow so large?
They grew in mineral-rich water held for a very long time just below about 58 °C, where gypsum was only very slightly favoured. Few crystals started, so those that did grew large. Inside Naica
Can I visit the Naica Cave of Crystals?
No. It was never a public site, access was limited to research teams, and after mine pumping stopped the lower levels flooded again. The Pulpí Geode in Spain offers guided visits.
Why are there seashells near the tops of mountains?
Rocks formed on ancient seafloors were lifted by plate collisions. The summit of Everest is marine limestone. Collision and uplift
About Our Explanations
Are the images on this site photographs?
No. They are soft-lit 3D renders of specimens and simplified cutaway models, made to show structure clearly. Models are labelled as explanatory and are not to scale.
How do you separate established science from hypothesis?
We label mechanisms supported by measurement and repeated observation as established, and mark ideas still under test, such as competing origins for Devils Tower. Our method