I'm recalling a technology from 70s Southern California: low-slope, tar paper for water seal, half-centimeter fragments of broken light-colored rock scattered o

I'm recalling a technology from 70s Southern California: low-slope, tar paper for water seal, half-centimeter fragments of broken light-colored rock scattered on top. Dust falls through the gaps onto the tarpaper. One downside being that after a heavy rain, some fraction of the gravel makes its way down from the roof.