1-Fossils: Intro
A fossil is an
imprint left behind from a past organism, many of thousands of years ago. There
are three main ways that fossils come into being; molds,
preserved
original materials, and replacement
fossils. Fossils are used to determine how or what lived in the past, what
it looked like and why it might have died. Found only in sedimentary rock
around the world, fossils are found where the conditions where perfect at
the time that it died/left a mark. Fossils found nearer to the earth's surface are presumably "younger"
than fossils found deeper in the earth's crust. Fossils that are
younger are similar to the animals of today, but the creatures of the
REALLY past are completely different. First, it must create an imprint by either
dying and the whole body would be fossilized; or it could have stepped across
mud; etc. Then, it must be covered quickly with mud or sand, before it is
composted or preyed on by raptors/disturbed by another creature/wind/rock fall; etc.
Next there must be chemicals nearby that preserve, like natron, and the
fossil is left undisturbed for thousands of years. This is where the
fossilization steps split. Next, the three ways are explained, and the
organism used to illustrate these processes is a hyracotherinum (four toed
horse that stood 30cm high, and is now extinct).