For many years geology was based on the belief that all landforms and the progress of evolution were in a gradual, uniform step. This was called The Theory of Uniformitarianism. The idea was that processes observable today were also observable in the past. In other words, if one could see silt deposited in a dust storm, it was safe to assume that in the past the same process would deposit silt.
As more evidence becomes available, it is becoming evident that there are times in the earth's history in which catastrophic events shape the surface of the earth. An example of this is the Washington Scablands, in Washington State, which are now believed to have been formed by the breach of a natural dam of a huge, glacial meltwater lake, in which billions of gallons of water swept over the plains west of the Rockies and formed a scoured, bizarre landscape while rushing to the low elevations. A modern example of this would be the devastation around Mt. St. Helens.
The current theory is that the evolution of the earth's surface is caused both by consistent, everyday processes (spring floods, sandsorms, stream erosion, beach deposition) and the odd but devastating catastrophes which shape landforms as well (catastrophic volcanic explosions, breaches of natural dams, comet, meteor, and asteroid hits, etc.).
No one with any scientific credibility believes that the earth was formed solely by catastrophic events.
Daughter #1 is coming in tonight, and I'm heading to Columbus to the airport to pick her up. My 'baby' sister is getting married on Saturday, and we're heading up to the Youngstown area for the wedding tomorrow.
Thanks for the information you're giving me. I'll give it some serious thought.