South Falls is the tallest waterfall in Silver Falls State Park, dropping a spectacular 54 meters off a basalt shelf. South Falls can be visited (along with nine other waterfalls) on the park’s great loop, the Trail of Ten Falls.
South Falls is the highlight of Silver Falls State Park, and due to its proximity to the city of Salem, is likely one of the most popular waterfalls in Oregon outside of the Columbia River Gorge. While South Silver Creek isn’t nearly as voluminous as North Silver Creek, South Falls will still swell to impressive volumes during the wet season and is without question the most powerful waterfall in Silver Falls State Park during the high water season.
Like all the other waterfalls in Silver Falls State Park, South Falls is formed where the creek has eroded away at layers of lava flows. The stream bed above the falls is flat and very gentle and this allows the stream to spread out over a considerable width, similar to several of the other waterfalls in the park. The bedrock constricts ever so slightly at the top of the falls such that the majority of the water does funnel into a much narrower plume as it drops over the falls, but during high water periods the falls may still expand to as much as 15m in width, but nothing quite as pronounced as either Lower South Falls or Middle North Falls.
South Falls is one of four waterfalls in Silver Falls State Park which features a trail passing behind the falls. Unlike at the other three waterfalls where this occurs, the overhanging cliff at South Falls is immensely tall, so it doesn’t so much feel like walking through a cave as it does taking shelter under a high forest canopy.
In several places where the trail does approach overhanging rock, there are many “skylights” visible in the rock, which were formed where the lava enveloped trees. As the lava cooled it hardened around the trees and then over time the wood decayed away, leaving empty holes in the cooled lava flows where they once stood.
According to the Internet