subglacial

/sʌbˈɡleɪʃəl/
adjective
  1. Located, formed, or occurring beneath a glacier or ice sheet.
    • Scientists discovered a subglacial lake buried under miles of Antarctic ice.
    • Subglacial volcanoes can cause massive floods when they erupt under an ice cap.
    • The subglacial landscape was carved by the slow movement of ancient ice.