Shiprock is the remnant central feeder pipe of a once much larger volcanic landform. It is 1700 feet high, and is composed of breccias or fractured volcanic rock. It is thought to have reached only 1000 feet below the original land surface and to have intruded into the Morrison Sedimentary Rock Formation.
If this is true, millions of cubic yards of strata have been removed since its formation. Up to 1700 feet thick strata, covering thousands of square miles around it, would have been erroded away. No present process does this at the magnitude needed (that I know of). As well, dating volcanic rock is problematic with highly variable isotope dates within samples of the same rock, and between different methods.
Shiprock appears to be a remnant of a flood event in which there was widespread breaking up of the continents after watery earthy matter had been deposited, and with subsequent volcanic activity and mass erosion.