The headwaters of the South Fork and the Table Rock Fork are basalts older than the Columbian basalts. They are part of the Sardine series volcanics. As the two irver forks join to form the main stem of the Molalla River, they begin cutting into the Stayton lavas. The basalts form narrow canyons where column rossetes and defined basalt columns can be seen mostly on the east side of the river.
The west side of the river has an over-lying layer of the Molalla formation. Carbon dating of fossil leaves, which are abundant in this area, has placed it in the upper Miocene period. The river cuts deeply into this formation creating narrow canyons and beautiful rock outcrops.
In pre-historic times, an extensive system of trails existed along the Molalla River. These trails provided a trade route between peoples of the Willamette Valley and those of Eastern Oregon.
The Molalla Indians used one such trail in the early 1800's. It is now called the Table Rock Historic Trail.
During the 1920's this same trail was utilized by Native Americans from the Warm Springs Reservation to reach traditional huckleberry picking areas near the Molalla River and Table Rock.
Euro-Americans began moving into the area during the late 1800's. They were searching for gold and looking for land on which to homestead. As the white settlement grew, so did commercial business. By the early 1900's, logging and mining companies were fully established in the Molalla River watershed.
Today, logging and recreational use are the primary activities in the upper reaches of the Molalla River.