metamorphic rocks. Though most rocks in the park are from the more recent Mesozoic, the oldest rocks are 400 million years old, dating from the Devonian. A complex assemblage of various rock formations have repeatedly been eroded, reburied, subjected to fracturing and heat, creating a geological puzzle that is one of the most complicated and least understood geological records in North America. These forces are ongoing and the region continues to see uplift and faulting. Evidence from the fossils and magnetism found in the rocks indicates that the terranes composing the North Cascades drifted thousands of miles north until they impacted the North American Plate 90 million years ago. The collision between the rocks caused fracturing and folding as well as uplift and the terranes were further fractured into north or south trending faults. The uplifted rocks mostly eroded away; 40 million years ago the heavier basaltic rocks of the ocean floor started to push the lighter granitic rocks that are the core of the mountains upward, a process that continues. Subjected to intense heat, rocks deep underground near the collision zone became recrystallized into granitic rocks, which comprise the backbone of the highest peaks. Continued uplift and erosion and finally the action of glacial ice on the landscape during the Holocene exposed the rocks visible today. Much harder and more durable than the younger volcanic rocks of the southern Cascades, the North Cascades are consequently more rugged, with steep terrain being the norm due to heavy erosion from water and ice. Continued rising in conjunction with erosion from water and ice has created deep valleys and significant vertical relief that is comparable to much taller mountain ranges. Mountains The tallest mountain in North Cascades National Park is Goode Mountain at . It lies in a remote backcountry region of the southern section of the park. Nearby are several other peaks that exceed , including Buckner Mountain () and Mount Logan (). At about , about northeast of Goode Mountain, is Black Peak (). Other prominent peaks in the southern section of the park include Boston Peak (), Eldorado Peak () and Forbidden Peak (). The northern region of the park contains the Picket Range, a subrange of the Skagit Range, which is in turn a subrange of the North Cascades. The Picket Range has numerous spires with ominous names such as Mount Fury, Mount Challenger, Poltergeist Pinnacle, Mount Terror,