There are several clearly definable types of place name, the primary division being between the names of natural features and the names of human settlements. That the latter are 'places' is obvious. The case is slightly more ambiguous for natural features, depending on how exactly 'place' is defined, and what exactly the concept of a 'place' is used for. If, as is probable, natural features were originally given names to distinguish nearby hills, streams etc. from each other, then these features can be thought of as places, in that they represent distinct geographic locations. However, as names are applied on a larger scale, they may become less useful as place names. For instance, a relatively small, distinct upland valley (e.g. Swaledale) clearly represents a definable geographic location. However, the broad, extended valley of a major river, such as the Trent, is not easily understood as a single location. That notwithstanding, it is probable that the origins of the names of both settlements and natural features is the same, namely to distinguish one from another; and thus that both should be considered place names.