Traumatic injuries, such as that suffered by christopher reeves (an actor that portrayed superman years ago) can affect a variety of functions of the body. the dysfunctions are dependent upon the level in the spinal cord the damage occurred and what aspect(s) of the cord is damaged. in this posting, you are to describe the organization schemes of the spinal cord (both anterior-posterior as well as internally).

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

hope this .. .

it creates acid rain