Years ago a large cloud of dust in space called a Nebula started to spin and come together. From this nebula our Sun formed. As the sun was forming smaller areas in the nebula began to also spin. These smaller areas swept up matter in the nebula and became the planets and their moons. 1"Earth formed 5 billion years ago, 3.7 billion years earths crust is solid, 3.5 billion years ago first life appears in the form of Bactria. 2.6 billion years ago oxygen is build up in the atmosphere,and 1 million years ago people ivloved." 2"Idex fossils are fossils used to define and identify geologic periods. They work on the premise that, although different s
ediments may look different depending on the conditions under which they were laid down, they may include the remains of the same species of fossil. If the species concerned were short-lived, then it is certain that the sediments in question were deposited within that narrow time period. The shorter the lifespan of a species, the more precisely different sediments can be correlated, and so rapidly evolving types of fossils are particularly valuable."
tp://www.worsleyschool.net/science/files/time/line.html
http://en.wikipedia.org/wiki/Index_fossil
ediments may look different depending on the conditions under which they were laid down, they may include the remains of the same species of fossil. If the species concerned were short-lived, then it is certain that the sediments in question were deposited within that narrow time period. The shorter the lifespan of a species, the more precisely different sediments can be correlated, and so rapidly evolving types of fossils are particularly valuable."
tp://www.worsleyschool.net/science/files/time/line.html
http://en.wikipedia.org/wiki/Index_fossil
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