Tag Archives: Missoula

Pacific Northwest Pt.2

Part 1 was about a couple of cultural borders. This time we address a physical geographical calamity of epic scale. I recently had the opportunity to make some simple maps of the Missoula Floods for a book that will soon be available about the Fanno Creek basin south-west of Portland, OR. The floods occurred occasionally around 13k to 15k years ago in the Pacific Northwest. The flood crested at about 400′ above sea level in the Portland area. 
The floods were the result of breeches in the ice dam that held massive glacial Lake Missoula in place. The lake held as much as half the volume of Lake Michigan! The Missoula Floods caused massive erosion stripping away topsoil and rock, basically scouring the landscape between Missoula and Portland and either on to the coast or down the Willamette Valley. The waters would eventually recede and deposit much of that fertile soil and the occasional erratic boulder in the Willamette Valley.
Amazing giant current ripples are still visible in the landscape of eastern Washington. This paper by Prof. Keenan Lee has some great images and info about giant current ripples.
The floods had an immediate physical impact across the PNW, but the impact on the social and cultural development of the areas persists today in many ways, ranging from what grapes grow best in the Willamette Valley to soil instability under houses perched on some over developed Portland hills.
The map below shows the location of Glacial Lake Missoula and the flood path. There are highlighted locations with specific significance to the Fanno Basin story, but you get the idea. An awesome amount of water traveled across what is now four states.
The detail box focuses on the Portland area inundation, shown below. The flow path is represented by arrows, and the flood crest is a 400′ contour. The current locations of some cities as well as the current path of the Columbia and Willamette rivers are also shown.

 As you can see, nearly the entire Portland area was under water. 

The opportunity to map the floods also gave me an idea for how to solve a map I had volunteered to make for NACIS 2012 in Portland, OR. Which is next week! Wahoo. 
The map is part of a collaborative project that some of the NACIS organizers put together. They sent a call for volunteers to map a tile in what is going to be a cartographic quilt. The Portland Urban Growth Boundary, UGB, was divided into tiles. Each tile was assigned to a naive volunteer cartographer. The tiles are shown here:

I was assigned the most north-easterly tile. It includes part of Oregon, Washington, and the Columbia River (Roll On).

My solution to avoid collecting transportation or other infrastructure data across state lines was to map the Missoula Floods. As mentioned, the high water mark in the Portland area is estimated to be about 400′ above current sea level.

All of the color map images in this post are from the map tile I created for that corner. I hadn’t opened Photoshop for a map project in a while, so it was fun to brush up on rusty skills, if not entirely effective map making.

There are some basic Photoshop techniques that played into creating this map. Patterns were used for the ground, ice, grass, and trees shown in the examples. The ‘Pattern Maker’ was successful for the ground/rock layer and the grass layer.

The ice layer looks a little too cloud like to me, especially close up, but I think it works OK at the intended resolution. The trees were given depth with both a slight drop shadow and bevel to the layer in PS. The sources for the patterns were gleaned from various air photos in Bing maps.

The water texture comes from a blank layer with filter->render->clouds applied  and then filter->sketch->chrome. Add some color and you’re good. I based the process on a few internet tutorials including this one. There is a simple hillshade and DEM under the flood layer to hint at depth.

The only reference to current physical geography (aside from the DEM being current data!) is the path of the Columbia River. It is severely muted. I think this would be too muted for the map on its own, but as a tile in a larger map, I think it will effectively continue the path of the river. I have to imagine that the others will highlight the river more than I have here, and hopefully create contrast between the river and floods that happened 13k-15k years ago.

Here is the whole tile, low res. I have left off scale and N arrow because this map will be combined with several others, and I think there will probably be a master scale and orientation to the whole thing. Annotation was kept minimal and muted to try not to conflict too much with other tiles which may or may not include text. I will try to post a copy of the entire quilt if I can after NACIS. We’ll see.

Since this is PNW pt.2, we need to add the lake and flood to our extentPNW map. Part one highlighted the cultural borders of the Oregon Country and the State of Jefferson. Those are still shown here with the addition of the Missoula Lake and Floods. The floods do not stretch the extent of the PNW as mapped, but certainly contribute to an understanding of an extraordinary historical event that connects much of the area. 

PNW Music Bonus!
Here is a little music from PNW band Finn Riggins. A great band from Boise. This tune seems appropriate for the theme of the Missoula Floods

For more about the floods I encourage you to check out  ‘Cataclysms on the Columbia’, a great overview of the Missoula floods.