What do all Maryland lakes have in common (besides water)?

There are about a dozen major types of lakes, meaning there are about a dozen ways lakes naturally form. None of those are found in Maryland. Some 74% of all lakes are glacial in origin, but glaciers never entered Maryland during the last Great Ice Age. Other major types of natural lakes include those that result from faulting, volcanic activity, and landslides blocking a river. But not in Maryland. All of Maryland’s lakes are man-made.