Earth History #1 Crossword

earliest era of earth history, ending 570 million years ago
a core sample that is typically removed from an ice sheet
between the end of the Precambrian eon and the beginning of the Ordovician period.
the state or process of a species, family, or larger group being or becoming extinct. "the extinction of the great auk"
a basic law of geochronology, stating that in any undisturbed sequence of rocks deposited in layers
a system of chronological dating that relates geological strata to time
any method of determining the age of earth materials or objects of organic origin based on measurement of short-lived radioactive elements
a fossil that is useful for dating and correlating the strata in which it is found
process of determining an age on a specified chronology in archaeology and geology
the remains or impression of a prehistoric organism preserved in petrified form
the science of determining the relative order of past events
the outermost layer of a planet