I’d say Davies is comparing your congress’s speed to the average speed of a glacier.
eg. The Greenland glacier was the fastest over the last few years:
“In the summer of 2012, the glacier reached a record speed of more than 17km per year – more than 46m per day.
”We are now seeing summer speeds more than four times what they were in the 1990s on a glacier which at that time was believed to be one of the fastest, if not the fastest, glacier in Greenland," Ian Joughin explained."
I’d say Davies is comparing your congress’s speed to the average speed of a glacier.
eg. The Greenland glacier was the fastest over the last few years:
“In the summer of 2012, the glacier reached a record speed of more than 17km per year – more than 46m per day.
”We are now seeing summer speeds more than four times what they were in the 1990s on a glacier which at that time was believed to be one of the fastest, if not the fastest, glacier in Greenland," Ian Joughin explained."