If you’ve ever heard about sinkholes near Alpena and wondered how they formed, you’re not alone. It’s one of those Northern Michigan surprises that catches people off guard. The answer starts with something called karst. Once you understand what karst terrain is, the landscape around Alpena, Presque Isle, and even parts of the Upper Peninsula starts to make a whole lot more sense. So, What Is Karst? Karst is a type of landscape formed when water slowly dissolves certain kinds of rock beneath the surface. These rocks are usually limestone or dolomite, which formed millions of years ago from ancient… Read More »




