ANSIs are areas of land and water that represent significant geological (earth science) and biological (life science) features.
Earth science ANSIs include areas that contain examples of rock, fossil and landform features in Ontario. These features are the result of billions of years of geological processes and landscape evolution.
Life science ANSIs are areas that contain examples of the many natural landscapes, communities, plants and animals found in the 14 natural regions of the province.
MNR identifies ANSIs that are 'provincially significant' by surveying regions and evaluating sites to decide which have the highest value for conservation, scientific study and education.