While traversing the slopes and hanging coulee channels on the west side of Wallula Gap I had a view across the gap to the Twin Sisters via an old ice age flood channel hanging above the gap. The Sisters sort of get lost in the grand scale of the high cliffs of the gap and are better appreciated closer up.
Twin Sisters just visible in the left center across the river
The Twin Sisters are made up of a single lava flow of the 15.5 million year old Frenchman Springs Member of the Wanapum Basalt. This was a big flow and reached the Oregon coast.
The Twin Sisters and Wallula Gap inspired early artists that were part of the early explorations in the area (a few decades after fur traders already had established trade routes).