There was one slide that showed a badly eroded massive and it was blamed on "severe LOP operation".  I have trouble understanding this link but maybe there's data to support it.

Ah… could someone tell me what  “severe LOP operation”   IS ?  

Or, stated another way - - is that   10 d  LOP ?    50 d LOP  ?    100 d LOP  ?    150 d LOP ?