Straight Creek Fault

The Straight Creek Fault (SCF) is the principal north-south strike-slip fault in the state of Washington, with a minimum of 90 kilometers (54 miles) of right-lateral offset, and a major geological structure in the North Cascade mountains, where it separates the pre-Cenozoic igneous and metamorphic rocks of the North Cascades on the east from the younger accreted terranes on the west.

Some geologists believe it does continue south, with all traces covered by more recent volcanic deposits.

Others have speculated that it simply ends, or turns and aligns with the OWL,[2] or has been offset elsewhere.

The SCF offsets the older NNW striking Entiat, Ross Lake, and Chewack-Pasayten faults, but not certain younger features,[4] the period of its strike-slip activity thus being bracketed between 47 and 41 million years ago (in the Eocene epoch), just after the wedge of crust now carrying the Olympic Mountains pushed into the continental margin.

[6] The SCF seems to be related to the Darrington—Devils Mountain Fault (DDMF), which runs due east from the southern end of Vancouver Island to the small town of Darrington, then turns nearly south to converge with the SCF near its intersection with the OWL.