There has been enormous change to the landscape in the long term past. Much is covered in the "Geology" section.

The eruptions would also have changed the water courses and formed many of the lakes in the district. Some are fresh and some are saline. This provides food for large numbers of birds.

Many fly down the western edge of the pacific ocean from north asia and Russia to feed here over the southern summer, then to return north for the northern summer.

So lakes Corangamite, Gnarpurt and Terangpom are designated RAMSAR wetlands.