Index fossil is a type of fossil that is widespread over a
large geographic range or area but in a short geologic time frame. Index fossil
are usually used in determining the geological periods because of its short
time frame, wide geological spread in area, and its rapid evolution.
Index Fossils are the type of fossils that has distinctive
characteristics, abundant in number, global in range and existed for a short
geological time frame. They are the best type of fossils in telling
time. Examples of index fossils are ammonites, brachiopods, crinoids, bryozoans, <span>rugose corals, mollusks and trilobites. </span>
Social security is the survival benefit for the family of wage earner who die. The blackout period can be defined as the gap that exists until which the deceased children and spouse does not receive the survivors benefit. In the blackout period the widow or widower who is not remarried will not receive the benefits before the age of 60. They will receive the security money as pension or retirement income of the deceased.
