It formed when a volcanic dome hardened and gradually eroded, exposing the onion-like layers of rock.
它也是在一个火山穹丘硬化和逐步侵蚀中，剥离出洋葱状岩石层形成的。
2
Although it resembles an impact crater, it formed when a volcanic dome hardened and gradually eroded, exposing the onion-like layers of rock.
尽管它看起来像是一个陨石撞击坑，它是在一个火山穹丘硬化和逐步侵蚀中，剥离出洋葱状岩石层的结果。
3
We get a good view of the capital's 13th-century city walls and turrets and the onion-shaped dome of the Alexander Nevsky Russian Orthodox church as we drive in along the coast road.