acclivity

ylärinne, ylämäki puhekieltä A slope or inclination of the earth, as the side of a hill, considered as ascending, in opposition to declivity, or descending; an upward slope; ascent.
(RQ:Grey Riders)

Just below it leaned a tottering crag that would have toppled, starting an avalanche on an acclivity where no sliding mass could stop.