Chuckanut Formation (part of the "Northwest Cascade System" of rocks shown in green on the map), an Eocene sedimentary formation which formed adjacent to the Swauk, Roslyn and other formations (also in green) south of Mount Stuart; their wide separation is attributed to right-lateral strike-slip movement along the SCF. That the northern part of the DDMFZ shows left-lateral strike-slip movement is not the inconsistency it may initially seem – think of the motion on either side of an arrowhead. It appears that what is now the DDMFZ was originally aligned on the OWL. Then about 50 Ma ago North America crashed into what is now the Olympic Peninsula along an axis nearly perpendicular to the OWL, pushing the rock of the Mesozoic (pre-Cenozoic) Western and Eastern Melange Belts (WEMB, blue on the map) across the OWL, bowing the DDMFZ, and initiating the SCF and thereby splitting the Chuckanut Formation. On the north side of the DDMFZ, and wrapping around a bit to the east side, is a suite of distinctive rocks – the Helena—Haystack mélange ("HH Melange" on the map) – which was collapsed into vertical folds. Similarly distinctive rock is found in Manastash Ridge (shown on the map, but almost too small to see) still lying on the OWL, just east of the SCF. This can explain an early puzzle as to why the Mesozoic rocks just south of the DDMFZ – the Western and Eastern Melange Belts – have no counterpart on the east side of the OWL and offset to the south: they were not faulted by the SCF, but were pushed against it from the southwest. Then it gets curiouser. Rock very similar to the WEMB (including a type called blueschist) is also found in the San Juan Islands, and along the West Coast fault on the west side of Vancouver Island. This suggests that the OWL was once a strike-slip fault, possibly a continental margin, along which terranes moved from the southeast. But similar rock also occurs in the Rimrock Lake Inlier, about 75 km south of the OWL and just west of the projected trace of the SCF, and also in the Klamath Mountains of southwestern Oregon. To account for the wide dispersal of this rock is difficult; many geologists see no alternative to transport along an extended SCF. But that upsets some of the "solutions" described above, and there is yet no consensus