How are swallow holes formed?
If you are referring to sink holes, they form when groundwater makes the ground unstable and it collapses.
Black holes can only be formed by the left overs of a supernova. A supernova is a gigantic explosion in which massive star collapses and throws the outerlayers into space. If the leftpvers of a supernova are more than three times bigger than the sun they may collapse further to form a black hole. NOTE: Black holes can only be created in space. If a black hole does occur it will not only swallow many…
Galaxies are formed when the gravitational pull comes together pushing stars in. Since black holes were extremely commmon at the birth of the universe, many galaxies own one, such as ours, the Milky Way. Galaxies such as the Sombrero and Andromeda have similar Holes. These holes are supermassive holes, giant gravity balls.