Lead climber pulled off a large block (big microwave sized) at the top of the gulley, which broke into pieces when hitting the ground. The rock hit the belayers leg causing a bruise.
When lowering off, the belayer realised the rock had also severed the rope on the floor by almost 75% so didn’t want to pass the rope through the grigri and take weight.
Climber was rescued by being dropped another rope and lowered by a second belayer.