ended by ~15,000 cal yr ago. Glaciers reformed in the highest cirques during a minor late-glacial readvance, the Recess Peak event, between about 14,200 and 13,100 yr ago. After that, glaciers appear to have been absent from the range until about 3200 cal yr ago, when small glaciers reappeared in the highest cirques. This readvance records the onset of Neoglaciation in the Sierra Nevada. Neoglaciation in the range culminated during the "Little Ice Age," a term originally coined by François E. Matthes in the Sierra Nevada, but now widely accepted as referring to a period of global glacial expansion between about AD 1250 to 1900. Moraines in the Sierra Nevada related to the Little Ice Age event are termed Matthes deposits. They are common in north-facing cirques and below modern glaciers in the High Sierra and are typically fresh, unstable, and often ice-cored. Good examples of Matthes moraines can be found below the Palisade Glacier (the largest glacier in the range), Lyell and Maclure glaciers in southern Yosemite N.P., and the smaller glaciers below Mount Dana, Kuna Peak, Mount Conness, and Matterhorn Peak. Glacial systems reached depths of up to 4000 feet (1200 m) and left their marks in the Yosemite area. The longest glacier in the Yosemite area ran down the Grand Canyon of the Tuolumne River for 60 miles (95 km), passing well beyond Hetch Hetchy Valley. Merced Glacier flowed out of Yosemite Valley and into the Merced River Gorge. Lee Vining Glacier carved Lee Vining Canyon and emptied into Lake Russell (the much enlarged ice age version of Mono Lake). Only the highest peaks, such as Mount Dana and Mount Conness, were not covered by glaciers. Retreating glaciers often left recessional moraines that impounded lakes such as Lake Yosemite (a shallow lake that periodically covered much of the floor of Yosemite Valley). Some domes in the park were covered by glaciers and modified into roche moutonnées, which are characterized by having a smooth, rounded side and a steep face. The rounded side was where the glacier flowed over the dome and the steep side is where the glacier flowed away from it. The steepness is caused by glacial plucking of rock along fracture joints. Good examples in the park are Liberty Cap, Lembert Dome, and Mount Broderick. Half Dome was created by a different process, but erosion acting on jointing planes was still the major factor. Controversy