as much as 166 million years old) collected in the accretionary wedge (or prism) of a subduction zone. The presence of detritus from the Idaho Batholith indicates a former location closer to southern Idaho. Some of these faults possibly developed in the Mesozoic, when these deposits were in the accretionary wedge; the cross-cutting NE and NNE-striking faults that form the various basins resulted from a subsequent change to transtension. Early Eocene igneous units in the area appear to be part of a 49- to 44- Ma magmatic belt that appeared just after the arrival of Siletzia, and possibly associated with that event. The strongly expressed topographical lineaments at the north end of the Rogers Belt pose a perplexing problem, as they show no definite offset where they are bisected by the left-lateral oblique-slip Devils Mountain Fault. The alternative, that younger faulting in the Rogers Belt has offset the DMF — Cheney argued that the MVF had offset the DMF 47 km. to the north, past Lummi Island — is contrary to the prevailing consensus that the DMF is not offset. Cherry Creek Fault Zone The Cherry Creek fault zone (CCFZ) was discovered in 2010 while mapping the area at the north end of the Rattlesnake Mountain fault zone (RMFZ). From a point just north of Carnation the eastern edge of the CCFZ (here it is about three-quarters of a mile wide) can be traced up Harris Creek, crossing the upper reach of Cherry Creek, eventually reaching the town of Sultan. Here the main strand on the western edge merges with the Sultan River Fault under the Sultan River. It is projected to extend past Lake Chaplain, and perhaps to the east end of Mount Pilchuck. It is deemed a "major active or potentially active" structure. In the crowded field of active or potentially active fault zones that have been discovered in the lower Snoqualmie Valley, the Cherry Creek fault zone is particularly notable because east of Duvall it passes through a hotspot of active seismicity, including the 1996 5.3 Duvall earthquake. Offsets in the east–west oriented Monroe Fault (south side of the Skykomish River), earthquake focal mechanisms, and kinematic indications show that the CCFZ is a left-lateral strike-slip fault, possibly with some oblique motion (up on the eastern side). The CCFZ appears to be related to the parallel Tokul Creek fault zone to the south; both appear to be conjugate