Chapters 8 & 9: Earth History & Geologic Time – Unit Objectives
E5.3g Identify a sequence of geologic events using relative age dating principles. (Ch. 8.1)
#1 - I can apply the Law of Superposition to rock layers to identify the sequence of geologic events shown
by them.
#2 – Following the Principle of Original Horizontality, I can use Cross-beds, Graded bedding & Ripple
marks as clues to use to determine the original orientation of the rock layers.
#3 - I can use faults and intrusions as clues to apply the Law of Crosscutting relationships to help
determine the sequence of events that occurred in a set of rock layers.
#4 – I can distinguish the difference between the 3 types of unconformities, and explain what uncertainties
each can cause when identifying the sequence of geologic events in a geologic column.
E5.3B Describe the process of radioactive decay and explain how radioactive elements are used to
date the rocks that contain them. (Ch. 8.2)
#5 - I can describe radioactive decay.
#6 - I can explain how radioactive elements are used to date the rocks that contain them.
E5.3e Determine the approximate age of a sample, when given the half-life of a radioactive substance
(in graph or tabular form) along with the ratio of daughter to parent substances present in the
sample. (Ch. 8.2)
#7 - I can calculate the age of a rock sample if given the half-life of the sample and the ratio of parent to
daughter isotope in the sample.
E5.3f Explain why C-14 can be used to date a 40,000 year old tree, but U-Pb cannot. (Ch. 8.2)
#8 - I can explain the difference between radiocarbon dating and other forms of radiometric dating.
#9 - I can explain what types of materials each type of radiometric dating is useful/not useful for & why.
E5.3D Describe how index fossils can be used to determine time sequence. (Ch. 8.3)
#10 – I can explain the characteristics a fossil must have to be considered an index fossil & why each
is necessary.
#11 –I can describe how index fossils can be used to determine time sequence.
E5.3C Relate major events in the history of the Earth to the geologic time scale, including formation
of the Earth, formation of an oxygen atmosphere, rise of life, Cretaceous-Tertiary (CT) and
Permian extinctions, and Pleistocene ice age. (Ch. 9)
#12 - I can identify when the Earth was formed on the geologic time scale.
#13 - I can identify when the formation of a modern oxygen-rich atmosphere was reached on the geologic
time scale.
#14 - I can explain what events were occurring on Earth during the time period that the oxygen rich
atmosphere was formed that led to its formation.
#15 - I can identify when the major developments in the rise of life (first organisms, dominance by marine
invertebrates, dominance by reptiles, dominance by mammals) on Earth occurred on the geologic
time scale.
#16 - I can explain what events were occurring on Earth during each of the time periods when each of the
different types of organisms became dominant that allowed them to take over as the dominant life
form on Earth.
#17 - I can identify when the Cretaceous-Tertiary (CT) and Permian extinctions occurred on the geologic
time scale.
#18 - I can explain what events led to Cretaceous-Tertiary (CT) and Permian extinctions.
#19 - I can identify when the Pleistocene ice age occurred on the geologic time scale.
#20 - I can explain what events led up to and were caused by the Pleistocene ice age.