The North Cascades features some of the most rugged topography in the Cascade Range with craggy peaks, ridges, and deep glacial valleys. Geological events occurring many years ago created the diverse topography and drastic elevation changes over the Cascade Range leading to various climate differences. : Copper, Fernow, Seven Fingered Jack, and Maude The history of the formation of the Cascade Mountains dates back millions of years ago to the late Eocene Epoch. With the North American Plate overriding the Pacific Plate, episodes of volcanic igneous activity persisted. In addition, small fragments of the oceanic and continental lithosphere called terranes created the North Cascades about 50 million years ago. During the Pleistoceneperiod dating back over two million years ago, glaciation advancing and retreating repeatedly scoured and shaped the landscape. Glaciation was most prevalent approximately, and most valleys were ice-free by. Uplift and faulting in combination with glaciation have been the dominant processes which have created the tall peaks and deep valleys of the North Cascades area. Subduction and tectonic activity in the area began during the late cretaceous period, about. Extensive volcanic activity began to take place in the oligocene, about 35 million years ago. Glacier Peak, a stratovolcano that is west of Napeequa Peak, began forming in the mid-Pleistocene. Due to Glacier Peak's proximity to Napeequa Peak, volcanic ash is common in the area.
Climate
Napeequa Peak is located in the marine west coast climate zone of western North America. Most weather fronts originate in the Pacific Ocean, and travel northeast toward the Cascade Mountains. As fronts approach the North Cascades, they are forced upward by the peaks of the Cascade Range, causing them to drop their moisture in the form of rain or snowfall onto the Cascades. As a result, the west side of the North Cascades experiences high precipitation, especially during the winter months in the form of snowfall. During winter months, weather is usually cloudy, but, due to high pressure systems over the Pacific Ocean that intensify during summer months, there is often little or no cloud cover during the summer. Because of maritime influence, snow tends to be wet and heavy, resulting in high avalanche danger.