Notice: "Cache seekers assume all risks and responsibilities involved in seeking this earthcache." “Just because it is there, doesn’t mean you have to seek the cache!” Don’t let earthcaching control you, but rather you control earthcaching.
Note: Small pieces of petrified wood under two inches may be found 100 feet down the east slope from the parking area where others have already dug. You may find smaller discarded fragments in this area. You will have to use a pick and shovel and spend the time to dig for larger pieces. The final will take you to an overlook view of the area for a full understanding of the fold.
Saddle Mountains Petrified Wood Beds is located on BLM land 5 miles north of the town of Mattawa, Washington and is open to the public with some restrictions. Read sign at way point 1.
Travel east for 1 mile from Mattawa, Washington on Road 24 SW and then turn north on Road R SW. Way point 3. BLM sign, Way point 5. stay left, at parking area, park at fence, walk around fence gate and hike south .25 mile to final.
The petrified wood beds on top of a Saddle Mountains began 14.7 million years ago when the Cascade Mountain range was very active, erupting and sending lahars (mud flows) down their slopes toppling and caring every living thing in their paths including trees of every variety. Conifers from the mountains sides to deciduous below were pushed into the marshes and lakes of the Columbia plateau. Think of the Toutle Lake filled with debarked and delimbed trees after the eruption of Mount St. Helens.
At this time great rifts opened and 100 feet thick lava flowed out of ground from south eastern Washington, north eastern Oregon as far as western Idaho across the wet lands. Not like a volcano but magma shooting out of hundred mile long cracks in the weak earth crust. This lava flowed into the lakes covering, preserving and protecting the tree trunks by basalt pillows in the flow.
Over time ground water dissolves and replaces the organic material with minerals such as silica creating petrified wood. Petrified wood is Washington States official state gemstone. Also, opal geode nodules may be found here. Of the many lava flows over time, only three times did the molten basalt pillows trap trees for modern humans to discover.
Millions of years later, upward thrust from tectonic pressures uplifted, cracked and creating a fault-core folds in the landscape called an anticline fold. The layer of tree encased basalt was push upwards and through erosion has now exposed the petrified wood. Think of a holding a strip of plywood and bending it end to end up to the point before it breaks. At the bend, sand down through to expose the first few layers of lamination.
To log this Earthcache, please send a private message to me with answers to the following questions.
1. From the parking area, walk east to where others have dug for petrified wood and geodes. Describe the shapes, sizes, colors and texture of the petrified wood shards found in the spoils or disgarded mounds or describe any petrified wood shards you found?
2. From ground zero (final location) discribe the basalt outcropping southeast across the gully that is in view.
Optional: Upload a photo to the page of local wildlife, unique vegetation or geology in the area.
Placed with permission and conjunction of the Field Manager: Bureau of Land Management Wenatchee field office, Spokane District
BLM provide information:
The Saddle Mountains are a mix of public (BLM) and private lands. Visitors need to be aware of property boundaries and to avoid trespassing on private land. R road SW is the best road to access the west end of the Saddle Mountains. Please note that other roads in the area may not be public (BLM or county) roads, and access is by permission only. There are a number of roads and trails that criscross BLM-managed lands on the west end of the Saddle Mountains. Please stay on existing roads and trails and practice Tread Lightly principles:
-travel responsibly
-respect the rights of others
-educate yourself with maps and information
-avoid sensitive areas
-do your part to model appropriate behavior,
At the present time, BLM does have petrified wood restrictions on sections 7, 11 and 13 (see map). For guidelines on non-commercial petrified wood collecting, please view information at this link:
Bureau of Land Management
Miocene–Pleistocene deformation of the Saddle Mountains: Implications for seismic hazard in central Washington, USA
Ginkgo Petrified Forest: Downtown Geology Lecture Series with Professor Nick Zentner
Geology of the Pacific Northwest: Virtual Field Site Priest Rapids