Rock Stories

The rather ordinary chunk of conglomerate pictured below is part of a far-ranging story. On Kolob Terrace Road a lava flow emerges at the top of a canyon. As it descends the canyon it lies on different layers, showing the canyon existed when the lava emerged. At one point the lava is underlain by a flood deposit. The flood was locally violent, transporting boulders of Shinarump conglomerate up to 2 feet in diameter. For the conglomerate to be included in this flood deposit, the quartzite cobbles that make up the conglomerate had to have been first formed from sandstone which before becoming sandstone had to be sand which before it became sand had to be rock. Once the sandstone had formed then it could be metamorphosed into quartzite which could then be broken into pieces and rounded by water action into cobbles and gathered by a flood into a massive layer of gravel which then could be cemented together to form a layer of conglomerate. Then that conglomerate could be broken up by a flood and turned into boulders of conglomerate and rolled by a flood into place so a lava flow could bulldoze it’s way across the top of the flood deposit. Neat story. But it doesn’t stop there. After the lava flow, water continued cutting the canyon so that today the lava flow appears to be perched on top a narrow ridge running down the middle of the canyon. Pretty cool. And I didn’t even mention the petrified wood next to the conglomerate in the flood deposit.


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