 and GPS technology. So there's no geospatial information. They're just photographs. So we had to stitch all of those photographs together to make three-dimensional models of the ice field. And then we also looked at the imprint, the footprint of the ice field at the Little Ice Age, that period of time that was a little bit colder when glaciers were a little bit bigger. And that was about 1770 in Alaska. So we could reconstruct it over multiple time periods