Abstract
Mudboils were measured at 183 locations in the arctic and subarctic regions of Canada. A consistent relationship was found between the internal and external characteristics of the mudboils, permitting the identification of three different types of mudboils. Low-center mudboils have a circular or irregular, flat central part surrounded by a peaty rim and are found in areas of poor drainage. Raised-center mudboils occur in better-drained areas and have a slightly domed or elevated center. Step mudboils develop on slopes, and their surface remains nearly level. The material in mudboils is about two-thirds medium grained; however, the raised-center type contains slightly more fine-grained material.