Huge Boulder Shows Power of Flood

On the morning of May 18, 1980, Mount St Helens exploded with a vengeance. The intense heat from the blast melted great quantities of snow and ice which mixed with volcanic and organic debris, forming huge mud flows (lahars) which bulldozed their way down several rivers and streams. One of these was Pine Creek.

The Pine Creek lahar scoured the stream bed to bedrock, picking up and carrying huge pieces of rock as it 'raced' towards Forest Road 25. It arrived about 30 minutes after the eruption in the form of a 9-metre (30-foot) wall of cement-consistency water and debris, travelling at nearly 65 kilometres an hour (40 miles per hour). The Pine Creek Bridge was ripped loose by the passing flowage. As the mud flow subsided it deposited part of its load.

Next day, forest service officials discovered the Pine Creek Boulder 'sitting' where the mud flow had dropped it — on Forest Road 25, 9 metres (30 feet) above the normal creek level. It was about 5 metres (17 feet) in diameter and weighed as much as six Indian elephants (37 tonnes)! Two cranes were required to move it to its present resting place beside the road.

Illustration from Grand Canyon: Monument to Catastrophe, Steven A. Austin, ICR Santee CA, 1994

The Pine Creek Boulder provides a modern example of the incredible power of moving water and debris. It may help us appreciate to a small degree the highly energetic processes operating during the worldwide Flood of Noah's day.

Another example lies in the Grand Canyon in Arizona, where boulders of Shinumo Quartzite have been deposited in the bottom of the Tapeats Sandstone (see diagram). They represent a catastrophic underwater debris flow occurring as the Flood initially advanced over what is now northern Arizona. One of these boulders is estimated to weigh almost 200 tonnes (that's the weight of about 33 elephants!).

The processes occurring during the Flood were of such great magnitude that they generally overwhelm our understanding. Only rarely do modern-day geologic events provide examples showing this degree of catastrophe. The Pine Creek Boulder gives us some idea of the mighty forces which must have operated during the Flood.