Rip-Up Clasts, California

As the gravel and sand coursed down slope, it occasionally swept up chunks of the muddy sides of its channel. A few of these clasts are preserved as mudstone, which is much softer than the conglomerate around it. Thus these particular rip-up clasts have largely eroded out of the surrounding rock, but enough of the shaly material is left to tell what once filled the holes. They may also be called mudstone clasts, intraformational or intrabasinal clasts, or clay chips.