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Deep Time and Changing Landscapes of the Yakima River Canyon By: Dr Dale Beeson, retired geologist



The Yakima River Canyon along state route 821 in Washington State is not only a beautiful and scenic area, but it also holds a rich geological history that spans millions of years. This immense amount of time can be very difficult to comprehend!  The combination of deep time and the dynamic forces of nature have shaped our landscape into what it is today. Let’s consider the fascinating story of the Yakima River Canyon and its ever-evolving landscapes.


Exploring Deep Time

To truly understand the changing landscapes of the Yakima River Canyon, we must take a journey through deep time. Deep time refers to the vast expanse of geological history, spanning billions of years.  The Earth has been shaped and reshaped many times culminating in the landscapes we see today.

The Yakima River Canyon began its formation around 16 million years ago during the middle Miocene epoch. At the time, the region was being inundated by Columbia River flood basalts. These highly fluid lavas were sourced from hundreds of fissures which tapped the Earth’s mantle in NE Oregon. Over millions of years, these massive volcanic eruptions covered the area with layers of basaltic lava, creating the foundations for the rugged canyon walls we see today.


The Forces at Work

While the Columbia River flood basalts played a significant role in the formation of Yakima River Canyon, it was the forces of uplift and erosion that truly shaped the landscape we see today.

Around 10 million years ago, tectonic activity in the area caused the land to slowly rise, forming the Yakima Fold Belt. This folding and uplift, combined with the powerful erosive forces of the Yakima River, carved out the deep and dramatic canyon we see today.

The Yakima River itself has played a vital role in shaping the canyon. Over time, the river and its tributaries have cut through the layers of basalt, exposing the underlying rock formations and creating the steep, towering cliffs that define the canyon walls. The erosive power of the water and its sediment load, combined with the freeze-thaw cycle of the region, has led to the sculpting of the canyon we see today.


Unearthing the Past

Studying the geological formations within the Yakima River Canyon provides valuable insights into the region's ancient past. One fascinating discovery is the nearby Ginkgo Petrified Forest, which offers a glimpse into the flora of the distant past. The Ginkgo Petrified Forest is the most diverse petrified forest in the entire world, with over 50 species of trees. Visitors to this site can see petrified logs and stumps of trees that once grew in this area more than 15 million years ago.

In addition to the Ginkgo Petrified Forest, the Yakima River Canyon has also yielded similar examples of petrified wood preserved between some of the lava flows of the Columbia River basalts. The remains of ancient camels, mastodons, and even mammoths have been discovered in the Central Washington area, providing a window into the diverse ecosystems that once thrived here.


A Dynamic Landscape

The Yakima River Canyon is not just a relic of the past; it continues to change and evolve to this day. Erosion caused by the powerful flow of this river shapes and reshapes the landscape, creating new features and eroding existing ones.

One visible example of this dynamic landscape is the presence of towering basalt cliffs. These cliffs are the result of the ancient lava flows known as the Columbia River flood basalts, which occurred around 15 million years ago. Over time, the flowing river has gradually eroded the softer underlying material, leaving behind these stunning rock formations.

The Yakima River itself is a dynamic and ever-changing force. During times of heavy rainfall or snowmelt, the river can swell and surge, causing significant erosion and reshaping of its banks. This continuous cycle of erosion and deposition has shaped the intricate network of channels and terraces that can be seen along the river's course.


Preserving and Appreciating the Canyon

Given the geological significance and natural beauty of the Yakima River Canyon, it is crucial to preserve and protect this area. Efforts have been made to establish conservation areas and promote sustainable practices that can help maintain the unique landscapes for future generations to enjoy.

The Yakima River Canyon is a popular destination for outdoor enthusiasts, offering a wide range of recreational activities. Visitors can explore the diverse ecosystems, hike along scenic trails, or even go whitewater rafting on the river. The canyon's rugged landscapes, abundant wildlife, and stunning vistas make it a truly remarkable place to experience the wonders of nature.

By appreciating and protecting this natural wonder, we can continue to learn from and be inspired by the deep time and changing landscapes of the Yakima River Canyon.

In conclusion, the Yakima River Canyon is not just a picturesque destination; it is a living testament to the forces of nature and the passage of time. From the Ginkgo Petrified Forest that offers a glimpse into ancient flora to the dynamic forces of uplift and erosion, this region has a story to tell. By exploring its geological formations, unearthing its rich past, and appreciating its ever-evolving landscapes, we can truly appreciate the deep time and changing landscapes of the Yakima River Canyon.  


Come and learn more about this fascinating canyon’s geologic past at the KEEN 25th GISS event on Saturday, May 11 at 9-10:30AM at the Umtanum Creek Recreation site.  You can find more details here: https://www.ycic.org/giss

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