Complex sentence: Skeleton Lake was given its name because overhead images of it resemble a skull, but it is also believed that it was given its name when the bones of an Ojibwa woman and her son were found on an island in the lake.
Split into simpler sentences: Skeleton Lake was given its name because overhead images of it resemble a skull. It is also believed that it was given its name when the bones of an Ojibwa woman and her son were found on an island in the lake.