relative dating

Question 1

law of superposition

Answer 1

rocks at the bottom of a sequence are oldedt

Question 2

original horizontality

Answer 2

we know if rocksare TILTED as most rocks are deposited horizontally

Question 3

way-up criteria

Answer 3

STRUCTURE:
desiccation cracks
graded/cross bedding
ripple marks
salt psuedomorphs 
imbricate structure
flute casts
SHOW ORIGINAL WAY UP

Question 4

cross cutting relationships

Answer 4

features that cut through rocks must be YOUNGER than the original rock

Question 5

included gragments

Answer 5

fragments from an older rock can be found in a younger rock which indicates erosion may have occurred before the next bed was deposited

Question 6

uncomformities

Answer 6

represent a break in deposition when erosion occurs leading to a gap in geological record

Question 7

what are zone fossils

Answer 7

fossils specific to a specific time zone used to date rocks

Question 8

what makes a good zone fossil

Answer 8

geologically widespread
rapid evolution
short timescale
well preserved

Question 9

how are realtive and radiometric dating used to create the geological timescale

Answer 9

recognition of fossils and the law of stratigraphy meant that rocks could be put into ERAS and PERIODS
Later, radiometric dating meant actual dates could be put on these eras and periods