Moho went way deeper than that.
It went deeper into the mantle than the mantle was believed to be at the time. (they had picked what was thought to be a thin area) It only stopped because there was no more support in congress.
The American moho project stopped at 600 feet. The Soviets drilled to 12 kilometers or 40,000 feet, but since they were drilling on land, they never made it past continental crust.