Testing Flood Geology

Did the bulk of geological features (canyons, mountains, valleys, etc.) form as the result of a single catastrophic flood a few thousand years ago? Were they formed solely by much slower gradual processes? Or were they formed by a combination of catastrophic and gradual processes? A 2002 flood in Texas provides a tool to evaluate the method by which individual canyons formed.

Young-earth creationists argue that most, if not all, the world’s major geological features formed during or shortly after a global flood (which they estimate happened around 4,000 to 5,000 years ago). In contrast, old-earth creationists (as well as mainstream geologists) argue that canyons, mountains, valleys, etc. formed throughout Earth’s 4.5 billion year history via both catastrophic and more gradual processes. A recent paper shows how scientists can continue to test which model best explains all of the data.

One difficulty in addressing canyon formation mechanisms is reproducibility. In other words, scientists observe only the final state of the canyon, not its state before and during formation. However, local events, such as the Texas flood, regularly create smaller scale canyons where the before, during, and final states are clearly seen. In 2002, flooding in Texas carved Canyon Lake Gorge. Scientists recorded a wealth of data on the volume of water flowing over the dam, the surrounding terrain (before and after the flood), and how much debris the flood carried away. Analyzing this data, they tested various models of the gorge-carving processes.1

Some of the interesting results they found included the following.

  • Canyon morphology depends strongly on rock type.
  •  Erosion and carving occurred more rapidly in softer or fractured rock than in harder, solid rock.
  • Plucking (where large blocks are fractured and carried away by the water) was the major mechanism for carving the canyon into the bedrock limestone.
  • The capacity of the water to carry the large debris ultimately limited how rapidly the canyon grew.  

During post-flood research, the team found many superficial features in the canyon (inner channels, knickpoints, and terraces). Traditionally, such characteristics are often used to infer slow formation over geological time. Thus, the research team’s discovery indicates that these kinds of features are not good indicators of the timescales involved in canyon formation. However, the researchers did find that their models, which utilized sediment transport and stress estimates from hydraulic reconstructions, predicted the timescales to within an order of magnitude. This indicates that such modeling could easily distinguish between a young-earth and an old-earth model for the carving of a formation like the Grand Canyon because the two models’ timescales differ by many orders of magnitude.

This new tool provides the opportunity to analyze geological features that appeared to form in ancient megafloods, not only on Earth but also on Mars. RTB expects such future analyses will continue to affirm the old-earth position that numerous processes operating on many different timescales formed the geology seen on Earth and Mars over the last 4.5 billion years.

1. Michael P. Lamb and Mark A. Fonstad, “Rapid Formation of a Modern Bedrock Canyon by a Single Flood Event,” Nature Geoscience, published online: June 20, 2010, http://dx.doi.org/10.1038/ngeo894.


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