Gradient buffering background layer in ArcGIS Desktop?

Question

I have a map that was created by a contractor working for my employer before I began. I am not sure what GIS software the map was created in but it has an effect I would like to be able to reproduce in ArcGIS 10.1.

The map seems to have a gradient, buffered layer on the outside of the Australia coastline layer. This layer grades out from dark grey to white. Sitting off the coast in my layout view I have the Australia with the extent area showing.

What I can't get is the gradient layer to gradient out behind the Australia extent part. In the maps I make Australia is in a separate data frame and I can't make the background of that data frame transparent.

I can't post the maps as I'm a new user but if someone can assist me I can send you directly the maps to explain better what I mean.

Answer 1

By the description of it, it looks like a multiple ring buffer that your colleague had created. Gradient can be set once you have the multiple ring buffer layer added to the map. To confirm if I thinking in the right direction, can you have a look at the attached image and confirm is your case looks similar to this one?

Answer 2

Alternatively, you can use Euclidean distance from distance toolbar, the output would be in raster, but you can classify it to any no. of classes or represent it by choosing any gradient in symbology options.