Lava Butte Flow and Deschutes River, Oregon - Places of Geologic Significance on Waymarking.com

The parking coordinates will put you in the parking lot at the East Benham Day Use Area, which is a Recreation Fee Site so a parking pass is required. From the parking lot follow the trail to Benham Falls. The waymark is located on the footbridge across the Deschutes River.

Please post your favorite photo taken on your visit.

Benham Falls is a major point of interest in Newberry National Volcanic Monument. The trail is usually accessible by car early May to mid-November, or longer.

From the bridge the three volcanic units that control the location of the Deschutes River are visible. The oldest unit are a group of 1,800,000 year old rhyodacite domes which are visible on the north side of the river across the bridge.
As Newberry Volcano has grown over the last half million years it has gradually been displacing the Deschutes River westward. Prior to 80,000 years ago, the Deschutes River was located somewhere to the east between Benham Buttes and Green Mountain (north of Lava Butte). About 80,000 years ago an eruption on the northwest flank of Newberry produce a large tube-fed basalt flow that moved north and west. Much of the flow passed through Lava River Cave and another branch went north to underlie Bend and extend almost to Redmond. This large flow covered the previous river channel and over time a new channel was established along the western edge of the flow against the edge of Benham Buttes. Over the next 70,000 years the river cut a new channel between the flow and Benham Buttes.
By 8000 years ago, the Deschutes River occupied a deep canyon from Bend to a point several mile upstream from Benham Falls. Here at the bridge, drilling for a proposed dam showed that there was a canyon nearly 100 feet deep. Then about 7000 years ago activity at Lava Butte produced lava flows that spread westward and spilled into and filled the deep canyon of the Deschutes from the Benham Falls area to Dillon Falls area with more than 100 feet of lava. This dam resulted in a lake which extended up river beyond the Sunriver area. As the lake rose, the lowest point was a low saddle on Benham Buttes and the lake began to overflow and cut the channel that is now Benham Falls. Sediments flowing into the lake filled the old river channel up to the outlet level at Bennham Falls.
From the bridge on the trail to Benham Falls, the rim rock you see to the south is the rim of the old river canyon and to the east (downstream) the flows from Lava Butte can be seen at the rivers edge.
For more details on the geology check here.