What causes sinkholes and can we predict when they will form? Geologist Daniel Doctor is here to answer all our questions about sinkholes, how they form, and anything else you've ever wondered about the geological phenomenon.

Top image: Sinkhole in Guatemala City 2007 (AP Photo/Str) / Bottom image: Great Blue Hole in Belize / USGS.


Doctor is a research geologist with the USGS where he specializes in the central Appalachian Great Valley region. He's also specialized in hydrology. He'll be joining us today from 10:00 a.m. - 11:00 a.m. (Pacific time), so start asking him questions in the comments now!