Unit 4.1 - 4.3 A Brief History of Earth Test Crossword
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                   
 
 
Down: 1) Bring back into one's mind; remember.2) The age of a rock in years.4) Atoms of an element with different numbers of neutrons.6) A thin layer of rock.7) The process of fossilization in which mineral deposits form internal casts of organisms. Carried by water, these minerals fill the spaces with organic tissue.10) Die out completely.12) A fossil that can be used to identify a specific period in time.13) Rare, preserving only certain remains under specific conditions.14) According to a fixed plan or a system methodically.17) At, toward, or from the side; or sideways.19) An ancient tree sap. Across: 3) A high pressured dark imprint.5) Age in comparison with other rocks, either younger or older.8) The rate of decay of unstable isotopes can be used to estimate the absolute ages of fossils and rocks.9) A thin layer of rock.11) A gap in the sequence of rock layers.13) Collections of fossils.15) Burrows tracks or fossilized feces.16) The time it takes for half of a given amount of an isotope to decay.18) The breakdown of unstable elements into stable elements.20) Fossils left behind when soft parts have the gate away.21) The study of rock strata.22) The unbroken and consistent existence or operation of something over a period of time.23) A seed-eating songbird that typically has a stout bill and a colorful plumage.
 

 

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