Multi-ringed basin

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; a multi-ringed basin could be described as a massive impact crater, surrounded by circular chains of mountains resembling rings on a bull's-eye. A multi-ringed basin may have an area of many thousands of square kilometres. An impact crater of diameter bigger than about is referred to as a basin. TOC In adjacent rings, the ratio of the diameters approximates :1 ≈ 1.41 to 1. To start, a peak ring crater has one peak-ring, i.e., a crater rim, which is generally circular, and a mountainous region which surrounds the basin center. A multi-ringed basin has an important difference, which is multiple peak-rings. In extremely large collisions, following the impact the rebound of the surface can obliterate any trace of the initial impact point. Usually a peak ring crater has a high structure with a terrace, and has slump structures inside of it. In 2016, research brought forward new theories about the lunar mare called Mare Orientale on Earth's Moon, as to how it formed. Multi-ring basins are some of the largest, oldest, rarest and least understood of impact craters. There are various theories to explain the formation of multi-ringed basis, however there is currently no consensus.