Once Upon an Ice Age

I remember the geology professor pausing in his lecture on the Ice Age and sighing wearily, like he had said the words a thousand times and was getting sick of it.

“I do not like the word RETREAT,” he said. “The glaciers did not RETREAT. They did not advance down in one direction, then turn around and march back in the other direction. They MELTED. The ice MELTED and the water DRAINED AWAY.”

Of course, this was well before the days of Global Climate Change, so perhaps our freshman class was not as savvy about things like melting ice. Still, the terminology makes a subtle but important difference. Water has shaped this planet in amazing ways, and it shouldn’t get short shrift. Especially when you consider the massive volume of water that was released when those towering Ice Age glaciers began to melt. In some cases—particularly in the Pacific Northwest—it made for some real drama: the Ice Age Floods.


The Ice Age Flood of Lake Bonneville

Lake Bonneville was an ancient Ice Age lake so big it covered almost half of Utah. (Today, the Great Salt Lake is a remnant of Lake Bonneville—a tiny puddle compared to its former self.) Lake Bonneville was a pluvial lake—in a landlocked basin fed by the heavy rains of the wet, cool climate of the Ice Age. On the northern side, Lake Bonnevile was walled in by a rocky ridge – a natural dam. In one place, today called Red Rock Pass, it was slowly eroding, the rocks giving way to the softer sands below.

Then, one day around 14,500 years ago…the dam broke.

Imagine…If you had been standing on the canyon rim at Swan Falls Idaho, above the Snake River, which today looks like this…


A watercolor I did that shows the present-day view from the canyon rim.



…you would have seen something like this…


There were people in the Snake River area back then – perhaps someone actually witnessed this…?



A 300-foot wall of water shooting down the canyon!

The force of the flow was so great, it ripped out chunks of the canyon walls and sent them hurtling downstream. Today, this is affectionately known as “melon gravel”. Here I am standing by one particularly large piece of melon gravel:


Several months ago, I was asked by my clients at Idaho Power to design a sign telling this story. Swan Falls is the site of one of their dams, and there is an interpretive kiosk that tells the story of the flood, as well as the history of the power plant and the Native Americans that once occupied the canyon in winter villages.

Here is the finalized design for the Flood Sign:

DDahnSwanFalls [Converted]



If you’re ever in the Boise area, take a drive out to Swan Falls and check it out. It’s well worth the hour drive, and if you like historic power plants, you can arrange for a tour of the very cool old plant, too.

Plus, the interpretive signs (installation due in 2014) are going to be pretty great.




Add your thoughts:

What do you think! Have you ever been to Swan Falls, or another site in the Snake River Canyon? Have you ever heard of the Ice Age Floods?


Learn More:


Read a short article and watch a cool slide-show

Read a longer, more in-depth article on Lake Bonneville and implications for climate change research

Visit the Ice Age Floods Institute

Check out one of my other posts about flowing water, including a section on the Missoula Floods


Is Weedy the new Wild?

We are fighting a war against alien invaders…and we’re losing. But there is increasing doubt as to whether the invaders are really our enemies. If treated right, could they actually become our friends? Is it time to rethink our attitudes about weeds?

A Pretty Good Piece of Turf

Whether it’s native species we have no liking for, or exotics we cannot tolerate, weeds cost us a lot of time, money and aching muscles. I’ve been thinking about this topic a lot lately, especially since reading ‘The Rambunctious Garden: Saving Nature in a Post-Wild World’, by Emma Marris. At first, the words post-wild world made me cringe—but I discovered I really liked much of her approach to the future of nature on planet Earth.

I won’t do a book review here—that has been done already by others—I’ll just discuss what I like best about the book, from a nature-lover/non-scientist point of view.

Marris challenges our current approaches to dealing with the growing problem of invasive species, which are generally accepted as the Number One threat to biodiversity. She makes some compelling arguments, using examples of conservation biology from around the world, and in the end—although she does not provide a clear plan for moving forward—she does lay out the general direction of what may be our best to save nature.



Marris goes to great lengths to convince us we need an attitude shift in thinking about conservation goals. Rather than focusing on an ideal of ‘pristine’—anything we consider non-native—we should be aiming toward a planet that is bursting with nature: diverse, thriving, and best of all, surrounding us in our daily lives. Nature is not just confined to the grand, magnificent National Parks and preserves. It should be all around us, every day. It won’t always be native species, though. We will need learn to exploit the potential of exotic species to contribute to biodiversity. She provides examples of biologists who are working in this area.

Appreciation for Nature on all levels

It’s not just the cute and fluffy parts of nature that merit our attention—it’s all kinds of nature. Rather than focusing only on preserving pockets of nature we value as ‘pristine’, we should aim toward a planet-wide blend of functioning ecosystems with a diversity of species. It includes preserving the wilderness we have left and doing what we can to control the worst invasive offenders, but also paying lots more attention to the spaces in between wilderness areas. They may not be magnificent or even very pretty by some standards. They might be buggy or look messy, overgrown or weedy. But if they are tended right, they will be rambunctious.

Exotics are everywhere – and it may be impossible to get rid of them. Do some of them have potential to add to conservation efforts and biodiversity?


Being “gardeners of the planet”

If people embrace the idea that nature should be everywhere—if we demand it—then we can vastly increase the total acreage devoted to conservation. She envisions every patch of ground—no matter how small—in cities, towns, and open spaces, being ‘gardened’ to have conservation value. Some can be left to go pseudo-wild (which may lead to interesting surprises), some can be tended more carefully, some may be more geared toward food production or recreation, but little spaces added together can amount to a huge net gain for conservation. They can serve as refuges for smaller, yet very important species, and as connectors to larger areas like parks and protected nature preserves. The value multiplies when communities cooperate with one another, making a kind of large ‘garden plan’ geared toward sustaining biodiversity. The deeper we get into global climate change, the more important this type of cooperation will be, but it is also a great opportunity to build community and for people to feel they are taking positive action.


Where to spend the money

As always, money is the biggest problem. My greatest fear about this book is that people might use it as an excuse to simply stop funding conservation at all, or discredit ecology entirely. A great deal of her book demonstrates how our efforts at controlling invasive species are often ineffective, both scientifically and economically. But, it’s taken us so long to get this far—to convince people to care about things like preserving habitats, endangered species, and global climate change. If we’re failing…then why keep trying? Why not just pave over everything and be done with it? Marris points out that the money we’re spending now can be more effective if we spend it differently, which makes sense…if enough people agree to try.


It all comes down to open space

Boiling it down, it’s land—not simply ripping out invasive plants—that is the key to a rambunctious future. And not just large tracts, but basically every square foot that is not paved or covered with a structure. We need to concentrate population growth in already developed areas, preserve more open space, and use all of our land better to encourage biodiversity everywhere, not just in parks. We all need to become gardeners of new, rambunctious nature.


What do you think?

Do you like the idea of rambunctiousness? Can you live with weediness? Would you like to see a world with nature spilling out from every spare inch? Can you live with some untidiness and share your area with small creatures, even if they are bugs? Have you read the book…what was your reaction?


To read an excerpt from the book:



A short interview with Marris and some interesting comments:



A longer interview with Marris from the Nature Conservancy Blog:



An essay by Marris featuring Seattle’s Schmitz Park:



Did you know we’ve officially entered a new Geological Epoch? To learn about the Anthropocene: