Apparently the ice was dug up to build a city.

• Link: https://www.msn.com/en-us/news/us/city-under-the-ice-nasa-scientists-find-abandoned-cold-war-military-base-in-greenland/ar-AA1uOYN4?ocid=hpmsn&cvid=b00f20f79b5745fdb058155f45d31a47&ei=1

I learned about Camp Century several years ago.

More details here:

• Link: https://en.wikipedia.org/wiki/Camp_Century