Washington's Ice Age Floods

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Why We Love It

During the last ice age, powerful floods shaped the rugged terrain in the eastern part of the US state of Washington. This award-winning Cascade Story Map tells the story of those floods and the landscape they left behind. We love the rich combination of static and animated maps, 2D and 3D graphics, photographs, and satellite imagery. The animated GIFs in the side panels explain key concepts, and well-labelled flood maps reveal the sequence of events. By artfully blending different aspects of the story across maps, graphics, and text, this story map creates an engaging self-paced experience.

Why It Works

Annotation and sequenced overlays for maps and photos serve to educate us quickly as we explore the geological evidence. We see how scientists were able to make sense of eastern Washington’s bizarre, unique landscape. This map works because of its skillful use of timing and storytelling. In particular, the low sun-angle Lidar map and false color hillshading blend into the story as we scroll. This technique brings geologic features into sharp relief. We see things as the geologists do, and get a sense of scale for the ice age flooding and aftermath.

Important Steps

Parse the information into logical, smaller sections and visuals—an important aspect of careful editorial choices in making great Story Maps.

Because this map shows things as they were and not as they are today, it required collaboration with scientists who have reconstructed historical data such as ancient lakes and glaciers.

Point cloud data collected by Lidar instruments (flown in survey planes) is used to create exceptionally detailed maps of 3D surface features (such as trees and sand bars) that are visualized in ArcGIS Pro.

Labels and annotations make or break a map. Create a consistent style and visual hierarchy to call attention to critical features. Employ text masking to improve legibility against busy backgrounds.


Data & Software

Maps of the floods are modified versions of glacial ice and ice age flood-affected areas collected by J.T. Silkwood. The interactive map used route data provided by the National Park Service.

Software included ArcGIS Desktop and Adobe Creative Cloud.


The channeled scablands image was created using a modified relative elevation model (also known as a height above river model) in order to visually emphasize the former flood channels across a large area of eastern Washington.


It took about three weeks overall. The Washington’s Ice Age Floods story map was fairly complex, and the team created much of the content while making the story map.

Ancient Landscapes


When showing ancient landscapes, be sure to orient the reader by including modern landmarks such as present-day cities and coastlines.

Better Communicated


Some facts are better communicated with charts and graphics, such as the animated comparison of modern versus floodwater volumes.

Auto Playing Animations


Consider using animated GIFs for auto-playing animations that cleverly reveal facts on a map and draw the eye to important landscape features.

More Information

Map Author


Washington Geological Survey, a division of the Department of Natural Resources (DNR)


In partnership with citizens and governments, the Washington State DNR provides innovative leadership and expertise to ensure environmental protection, public safety, perpetual funding for schools and communities, and a rich quality of life.

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