If the cirque is subject to seasonal melting, the floor of the cirque most often forms a tarn (small lake) behind a dam, which marks the downstream limit of the glacial overdeepening.
https://www.nsa.gov/helpful-links/nsa-foia/declassification-transparency-initiatives/historical-releases/view/article/3880193/capt-grace-hopper-on-future-possibilities-data-hardware-software-and-people-1982/