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English: How crater-depth is measured, using the side-view of a typical crater. Depth "A" measures from the surface to the bottom of the crater. Depth "B" measures from the mean height of the rim to the bottom of the crater.
The depth of an impact crater in a solid planet or moon may be measured from the local surface to the bottom of the crater, or from the rim of the crater to the bottom. Crater depth diagram. The diagram above shows the full (side) view of a typical crater. Depth "A" measures from the surface to the bottom of the crater.
The largest in the last one million years is the 14-kilometre (8.7 mi) Zhamanshin crater in Kazakhstan and has been described as being capable of producing a nuclear-like winter. [11] The source of the enormous Australasian strewnfield (c. 780 ka) is a currently undiscovered crater probably located in Southeast Asia. [12] [13]
A central-peak crater is the most basic form of complex crater. A central-peak crater can have a tightly spaced, ring-like arrangement of peaks, thus be a peak ring crater, though the peak is often single. [3] Central-peak craters can occur in impact craters via meteorites. An Earthly example is Mistastin crater, in Canada. [1]
Valhalla Basin on Jupiter's moon Callisto, taken by Voyager 1. A multi-ringed basin (also a multi-ring impact basin) is not a simple bowl-shaped crater, or a peak ring crater, but one containing multiple concentric topographic rings; [1] a multi-ringed basin could be described as a massive impact crater, surrounded by circular chains of mountains [2] resembling rings on a bull's-eye.
In any case, users of a model need to understand the assumptions made that are pertinent to its validity for a given use. Building a model requires abstraction. Assumptions are used in modelling in order to specify the domain of application of the model. For example, the special theory of relativity assumes an inertial frame of reference.
Pit crater chains are distinguished from catenae or crater chains by their origin. When adjoining walls between pits in a pit crater chain collapse, they become troughs . In these cases, the craters may merge into a linear alignment and are commonly found along extensional structures such as fractures, fissures and graben.
For example, the Ishim impact structure [141] is conjectured to be bounded by the late Ordovician-early Silurian (c. 445 ± 5 Ma), [142] the two Warburton basins have been linked to the Late Devonian extinction (c. 360 Ma), [310] both Bedout and the Wilkes Land crater have been associated with the severe Permian–Triassic extinction event (c ...