On what date did the 1980 eruption of Mount St. Helens, in which "Crater Glacier" was formed, occur?
Crater Glacier The Crater Glacier (also known as Tulutson Glacier) is a geologically young glacier that is located on Mount St. Helens, in the U.S. state of Washington. The glacier formed after the 1980 Eruption and due to its location, the body of ice grew rapidly, unknown to the public for nearly 20 years. The glacier once contained ice caves in the smooth ice before the 2004-2008 volcanic activity. The growth of the lava dome and volcanic eruptions from 2004 to 2008 significantly altered the appearance of the glacier. In the same time period, several agencies decided to put an official name on the glacier which, at first, was Tulutson Glacier. A later decision made Crater Glacier the official glacier name. Despite the volcanic activity, the glacier continued to advance and by mid-2008, the glacier completely encircled the lava domes. In addition, new glaciers (rock or ice) have formed around Crater Glacier as well.
Gibran (crater) Gibran is a crater on Mercury, which was discovered in January 2008 during the first flyby of the planet by MESSENGER spacecraft. It contains a large (29 × 29 km ), nearly circular pit crater. Multiple examples of pit craters have been observed on Mercury on the floors of impact craters, leading to the name pit-floor craters for the impact structures that host these features. Unlike impact craters, pit craters are rimless, often irregularly shaped, steep-sided, and often display no associated ejecta or lava flows. These pit craters are thought to be evidence of shallow volcanic activity and may have formed when retreating magma caused an unsupported area of the surface to collapse, creating a pit. They are analogs of Earth's volcanic calderas. Pit-floor craters may provide an indication of internal igneous processes where other evidence of volcanic processes is absent or ambiguous. The discovery of multiple pit-floor craters augments evidence that volcanic activity has been a widespread process in the geologic evolution of Mercury's crust.