ROCKS - FOSSILS Flashcards
What are fossils?
It is signs or proof that organisms lived thousands of years ago.
It is organic material (plants and animals) that were compacted for a long time and formed rocks.
Name 2 types of Fossils and explain
Body Fossils - the body of plants or animals remains like bones or seeds
Trace Fossils - shows to the animals or plants activities like footprints or eggshells
In which rocks do we find fossils
Sedimentary Rocks
How does sedimentary rocks form?
When sand, mud or gravel are deposited in large water masses, by wind or other weather conditions it sinks to the bottom of the lake or ocean.
When animals are trapped in these layers, fossils will form over thousands of years, because of the pressure these layers of sediment and water cause
What is the more common fossils?
aquatic organisms (water animals) or
terrestrial organisms (land animals)
Aquatic organism, but terrestrial organisms have been found in rivers and lakes.
What do we find in fossils?
Mainly the hard part of living organisms, like bones or shells, seeds or woody parts of plants. The softer tissue like muscle and skin and organs decompose.
Name the 6 steps how fossils form / preserve
When organisms is quickly covered
Preserve without change
Repalcement of mineral
Imprints proof of life
Thin Layer of Carbon
Petrifaction
Fossils when annimals are quickly covered, explain.
Organisms is covered quickly after death:
Some animals are covered quickly before predators can eat them and sink into the mud or covered by sand.
When does annimals preserve without change, explain
Preserve without change:
Animals that get trapped in ice or tree resin, called amber (harden resin from pine trees is a gemstone) is preserved whole. Some animals in ice still have their fur.
When minerals are involved in the fossilation, name and explain
Replacement of mineral:
When the hard parts (bones) decompose it is replaced by minerals like iron, parts can clearly be seen.
When we find footprints of animals what fossilation took place and how?
Imprints proof of life:
When organism make imprint in mud or sand and the sediment hardens without being disturbed it can be trapped in rock. This proves live in a region/area.
What fossilation took place when we can only see a thin shadow of an print
Forming Thin layer of carbon:
When an organism with soft tissue is covered in sediment the tissue is exposed to high temp and pressure. These conditions take all moisture out the tissue and a thin layer of carbon is left behind creating a silhouette of the the organism.
What do we name the fossilation where all of the animal gets fossilized? The hard and soft tissue/organs
Petrifaction:
Is when hard (bone and teeth) and soft tissue (muscles and organs) of organisms are trapped in rocky minerals, eg. wood
