I'm trying to create an outline of a complex polygon. The polygon in question can be seen here (edit: I've attached the images below). This is an elevation model of an alluvial flow. As you can see, there are many little "islands" in the middle of the flow. I just want the greater outline of the flow, as demonstrated here (a poor hand-made outline in MS Paint...). For a sense of scale, this is about 10 km wide.
The attribute table for the polygon only has a single row, so I can't just edit out the islands. I've tried Buffer, Dissolve, and Union, all basically end up looking about the same.
Any advice on how to proceed would be appreciated.
Thanks
Dave
