360,000 years ago the entire north side of the volcano collapsed, creating an enormous landslide or debris avalanche, in volume. The slide flowed northwestward into Shasta Valley, where the Shasta River now cuts through the flow. What remains of the oldest of Mount Shasta's four cones is exposed at Sargents Ridge on the south side of the mountain. Lavas from the Sargents Ridge vent cover the Everitt Hill shield at Mount Shasta's southern foot. The last lavas to erupt from the vent were hornblende-pyroxene andesites with a hornblende dacite dome at its summit. Glacial erosion has since modified its shape. The next cone to form is exposed south of Mount Shasta's current summit and is called Misery Hill. It was formed 15,000 to 20,000 years ago from pyroxene andesite flows and has since been intruded by a hornblende dacite dome. There are many buried glacial scars on the mountain that were created in recent glacial periods ("ice ages") of the present Wisconsinian glaciation. Most have since been filled in with andesite lava, pyroclastic flows, and talus from lava domes. Shastina, by comparison, has a fully intact summit crater indicating Shastina developed after the last ice age. Shastina has been built by mostly pyroxene andesite lava flows. Some 9,500 years ago, these flows reached about south and north of the area now occupied by nearby Black Butte. The last eruptions formed Shastina's present summit about a hundred years later. But before that, Shastina, along with the then forming Black Butte dacite plug dome complex to the west, created numerous pyroclastic flows that covered , including large parts of what is now Mount Shasta, California and Weed, California. Diller Canyon ( deep and wide) is an avalanche chute that was probably carved into Shastina's western face by these flows. The last to form, and the highest cone, the Hotlum Cone, formed about 8,000 years ago. It is named after the Hotlum glacier on its northern face; its longest lava flow, the Military Pass flow, extends down its northeast face. Since the creation of the Hotlum Cone, a dacite dome intruded the cone and now forms the summit. The rock at the summit crater has been extensively hydrothermally altered by sulfurous hot springs and fumaroles there (only a few examples still remain). In the last 8,000 years, the Hotlum Cone has erupted at least eight or nine times. About 200 years ago the