2.  Fossils -evidence of ancient life forms or ancient habitats which have been preserved by natural processes. They can be the actual remains of a once living thing, such as bones or seeds, or even traces of past events such as dinosaur footprints, or the ripple marks on a prehistoric shore. Fossils can be used to recognize rocks of the same or different ages  Rocks- a naturally occurring solid aggregate of one or more minerals or mineraloids. It is also composed of grains of minerals, which, in turn, are homogenous solid formed from a chemical compound that is arranged in an orderly manner.

3. Early fossil discoveries In the 17th century, Paleontologist Nicholas Steno shook the world of science, noting the similarity between shark teeth and the rocks commonly known as "tongue stones". This was our first understanding that fossils were a record of past life. Two centuries later, Mary Ann Mantell picked up a tooth, which her husband Gideon thought to be of a large iguana, but it turned out to be the tooth of a dinosaur,Iguanodon. This discovery sent the powerful message that many fossils represented forms of life that are no longer with us today. Nicholas Steno's anatomical drawing of an extant shark (left) and a fossil shark tooth (right). Steno made the leap and declared that the fossil teeth indeed came from the mouths of once-living sharks.

4. Indication or Interactions Clues at the Cellular Level T his ammonite fossil (see left) shows punctures that some scientists have interpreted as the bite mark of a mosasaur, a type of predatory marine reptile that lived at the same time as the ammonite. Damage to the ammonite has been correlated to the shapes and capabilities of mosasaur teeth and jaws. Others have argued that the holes were created by limpets that attached to the ammonite. Researchers examine ammonite fossils, as well as mosasaur fossils and the behaviors of limpets, in order to explore these hypotheses. Fossils can tell us about growth patterns in ancient animals. This is a cross-section through a sub-adult thigh bone of the duckbill dinosaurMaiasaura. The white spaces show that there were lots of blood vessels running through the bone, which indicates that it was a fast-growing bone. The black wavy horizontal line in mid-picture is a growth line, reflecting a seasonal pause in the animal’s growth.

5. Possibilities of Fossil Formation Possibilities of Fossil Formation

6. -mold fossils- a fossilized impression made in the substrate - a negative image of the organism. -cast fossils - formed when a mold is filled in -trace fossils = ichnofossils fossilized nests, gastroliths, burrows, footprints, etc. -true form fossils -fossils of the actual animal or animal part.

7. Mold FossilCast Fossil Trace FossilTrue Form Fossil

8. unaltered preservation like insects or plant parts trapped in amber, a hardened form of tree sap. Permineralization = petrification in which rock-like minerals seep in slowly and replace the original organic tissues with silica, calcite or pyrite, forming a rock-like fossil - can preserve hard and soft parts - most bone and wood fossils are permineralized. replacement -An organism's hard parts dissolve and are replaced by other minerals, like calcite, silica, pyrite, or iron. carbonization=coalification in which only the carbon remains in the specimen - other elements, like hydrogen, oxygen, and nitrogen are removed. Recrystalization- hard parts either revert to more stable minerals or small crystals turn into larger crystals. authigenic preservation- molds and casts of organisms that have been destroyed or dissolved.

10. -Rocks provide evidence for changes in the Earth. In 1785 James Hutton presented his idea of a rock cycle to the Royal Society. He detailed ideas of erosion and sedimentation taking place over long periods of time, making massive changes to the Earth’s surface. -Rocks also serves as evidence of the changes undergone by plates and continents.

11. -Earth's magnetic field is the magnetic field that extends from the Earth's interior to where it meets the solar wind, a stream of charged particles emanating from the Sun.

12. Geomagnetic models form the foundation of traditional, compass-based navigational systems. These models provide a picture of the Earth's magnetic field and how it varies from one point on the Earth's surface to another. The primary world model is the International Geomagnetic Reference Field (IGRF), compiled from magnetic measurements collected by national observatories in many countries, as well as readings made from ships, airplanes, and satellites. The model, derived through mathematical analysis of a vast amount of data, represents the magnetic field generated in the Earth's core, with small-scale variations at the surface and solar effects filtered out of the basic data. Even in an age of Global Positioning System (GPS) navigation, when finding your position on the Earth's surface is just a click away, the geomagnetic model still plays a vital role, it is built into GPS navigation systems as a backup. The geomagnetic field model is also vital to various kinds of magnetic surveys, such as those used in mineral exploration and the mapping of hazardous earthquake faults

13.  The Earth's magnetic field is generated within its molten iron core through a combination of thermal movement, the Earth's daily rotation, and electrical forces within the core. These elements form a dynamo that sustains a magnetic field that is similar to that of a bar magnet slightly inclined to a line that joins the North and South Geographic Poles. A compass placed in this magnetic field thus does not point due north, declination measures the angle between the compass reading at any point on the Earth's surface and true north (measured in degrees). The geomagnetic reference model is the basis for establishing the declination and its variation across the surface of the globe.

14.  The direction and strength of the magnetic field can be measured at the surface of the Earth and plotted. The total magnetic field can be divided into several components:  Declination (D) indicates the difference, in degrees, between the headings of true north and magnetic north.  Inclination (I) is the angle, in degrees, of the magnetic field above or below horizontal.  Horizontal Intensity (H) defines the horizontal component of the total field intensity.  Vertical Intensity (Z) defines the vertical component of the total field intensity.  Total Intensity (F) is the strength of the magnetic field, not divided into its component parts.

15.  Inclination  Total Intensity

16.  The intensity and structure of the Earth's magnetic field are always changing, slowly but erratically, reflecting the influence of the flow of thermal currents within the iron core. This variation is reflected in part by the wandering of the North and South Geomagnetic Poles. Because a wide range of commercial and military navigation and attitude/heading systems are dependent on models of the magnetic field, these models need to be updated periodically. The magnetic field's strength and direction and their rates of change are predicted every 5 years for a 5- year period.

17.  Electrical particles streaming from the sun cause the "solar wind" which warps Earth's geomagnetic field lines, flattening them on the sun- ward side and stretching them out on the downstream side. The influence of this distortion of the geomagnetic field is quite small near Earth's surface (except during solar eruptions associated with sunspots) and becomes larger with increasing distance from Earth.

18. http://evolution.berkeley.edu/evosite/lines/I fossil_ev.shtml http://pubs.usgs.gov/gip/fossils/succession.html http://www.enchantedlearning.com/subjects /dinosaurs/dinofossils/Fossiltypes.html http://hyperphysics.phy- astr.gsu.edu/hbase/geophys/platevid.html http://hyperphysics.phy- astr.gsu.edu/hbase/geophys/platevid.html http://www.bbc.co.uk/nature/fossils http://nationalatlas.gov/articles/geology/a_ge omag.html#one