In August 1986, a gigantic volume of belched forth from Lake Nyos in Cameroon and swept down the adjacent valleys asphyxiating 1,700 people.

carbon dioxide

Explanation:

In August 1986, a gigantic volume of carbon dioxide belched forth from Lake Nyos in Cameroon and swept down the adjacent valleys asphyxiating 1,700 people. Lake Nyos is a lake in the Northwest Region of Cameroon. In 1986, Lake Nyos suddenly emitted a large cloud of due to a landslide. As a result, 3,500 livestock in nearby towns and villages.

they have different colored collars

radioactive dating, also known as  radioisotope dating  is a process that in  estimating the approximate  age  of  rocks. these data can be analyzed from  the studies dealing with the  decay of the radioactive elements that are present in these rocks. in nature, there are a few types of materials or atoms which are quite unstable and they spontaneously decay or breakdown to form other kinds of atoms.