WEBVTT FILE 1 00:00:00.000 --> 00:00:02.370 Scientists using ice-penetrating 2 00:00:02.390 --> 00:00:03.930 radar data from NASA 3 00:00:03.950 --> 00:00:07.520 have built the first-ever comprehensive 3-D map 4 00:00:07.540 --> 00:00:10.460 of the layers deep inside the Greenland Ice Sheet. 5 00:00:10.480 --> 00:00:12.910 This highlights how the ice sheet evolved 6 00:00:12.930 --> 00:00:14.470 and how it's flowing today. 7 00:00:14.490 --> 00:00:15.028