How Catastrophic Outburst Floods May Have Carved Greenland’s ‘Grand
                            2020-04-30 04:00
                        
                    
                            For years, geologists have debated how and when a network of canyons under the Greenland Ice Sheet formed, especially one that is so deep and long it’s called ‘Greenland’s Grand Canyon.’ Its shape
                        
                         
                                                         
                                                        