Rose here –
A couple of years ago my mom and I took a road trip to eastern Washington state to visit Drumheller Channels in the Columbia National Wildlife Refuge. This is an area containing giant basalt columns, part of the Columbia River Basalt flows, as well as some of the landscape known as the Channeled Scablands, remnants of the catastrophic Ice Age floods (check out the Ice Age Floods Institute for more info).
The Columbia River Basalt Group (CRBG) is a large igneous province in eastern Washington. Large igneous provinces are usually made of very low viscosity (runny) lava which has erupted from fissures in the ground and spread out to cover a large area. The CRBG is a series of lava flows (more than 350!) that cover an area of about 163,700 km2 (63,200 mi2). These lava flows altogether are more than 1.8 km (5,900 ft) thick. These flood basalt eruptions occurred from about 17 million years to about 5 million years ago
As basalt cools, it forms a hexagonal pattern on the cooling surface exposed to the air, similar to the pattern you see in mud as it dries. From the side this pattern looks like rows of columns next to each other, and beautiful landscapes made up of several stacked flows of this “columnar basalt” are a common sight as you drive through eastern Washington. The other major component of the eastern Washington landscape, the Channeled Scablands, are the result of flooding that occurred toward the end of the last ice age. They are called Channeled Scablands because the landscape consists of many interconnected channels and coulees and appears very rugged. This landscape has turned out to be one of the most important pieces of evidence in shaping our current understanding of how geological processes have shaped the surface of the Earth.
Before J Harlen Bretz started studying this landscape in the 1920s, geologists thought all Earth processes were extremely slow and gradual in making any changes in the landscape. This was a reaction to the suggestion by young earth creationists that the earth was formed rapidly by catastrophic events. The response of geologists to this idea was to immediately dismiss any hypothesis that the landscape had formed rapidly and insist that everything had happened very slowly and gradually. J Harlen Bretz became interested in some interesting erosional features he saw in eastern Washington and began doing intensive fieldwork in the area in 1922. As he continued to map and record his observations of the features he saw there, he became more and more convinced that this landscape had not been formed gradually but had been shaped by giant floods from further east. There are giant ripples here, giant channels and coulees, and giant “potholes” where rock has been plucked up by water rushing past. These features could not be explained by very slow and gradual erosion. Today, geologists understand that while many features are formed slowly, the landscape has also been formed in places by catastrophic events, some of which we can see today in volcanic eruptions, earthquakes, and tsunamis.
If you want to know more, here are a couple of good books to start with. Check with your local public library!
Bretz’s Flood: The Remarkable Story of a Rebel Geologist and the World’s Greatest Flood by John Soennichsen
Timefulness: How Thinking Like a Geologist Can Help Save the World by Marcia Bjornerud