Geologic Time Crossword Puzzle
QUESTIONS LIST: trace fossil : remains of plants or animals that were very abundant and existed briefly
, cyanobacteria : microscopic,photosynthetic prokaryotes
, epoch : time unit in the geologic time scale smaller than a period
, index fossil : indirect fossil evidence,like footprints,of an organism
, cenozoic era : "present" time period
, mass extinction : occurs when an unusually large number of organisms disappear from the rock record at the same time
, radiocarbon: _ dating - establishing the order of past geographic events
, half life : the period of time it takes for one half of a radioactive istope to decay
, precambrian : unit of geologic time when earth formed and became hospitable for life
, period : third longest time unit in the geologic time scale
, radiometric : _ dating - determines the age of a rock or fossil by determining the ration of parent to daughter nuclei
, mesozoic era : "middle" time period
, paleozoic era : "ancient" time period
, era : second longest time in the geologic time scale
, relative dating : determines the age of organic objects that were once alive
, eon : longest time in the geologic time scale