ENVIRONMENTS THROUGH TIME (Spotlight: pp 44 - 47 )
1. Conditions on early Earth were described as Anoxic. What does this mean?
2. Identify 4 atmospheric gases that made up Earths early atmosphere.
3. What are Banded Iron Formations? How did they form?
4. Name, from lowest to highest, the 4 main layers of the earth's atmosphere.
5. Identify the atmospheric layer which incorporates the Ozone Layer. What role does the ozone layer have
on Earth?
6. Differentiate between Ozone and Oxygen by completing the table below:
Oxygen
Ozone
Chemical Formula
Structural representation
7. Fill in the blank spaces using the word list below.
The Cambrian Explosion
aquatic, species, ozone layer, superposition, strata, fossil record, periods, older, UV, terrestrial,
phanerozoic.
Prior to the formation of the ___________ ______________, terrestrial environments were subjected to
lethal levels of ______________ radiation. Organisms are thought to have evolved from ______________
to ________________ environments around 500 mya.
The Cambrian Explosion marks a period of time noted for the evolution of many new ______________ .
Changes occurring to living things over time can be seen in the ______________ _________________.
Most fossils are located within sedimentry rock layers called _______________. Generally, the deeper a
fossil is located in rock strata, the _________________ it is thought to be. This concept is referred to as the
Law Of _______________________.
This basic principle has allowed geologists to divide up the current ________________ eon into several
smaller eras and _________________.
Fill in the details of GEOLOGICAL TIME SCALE in the table below (See table 2.2, p48 Spotlight).
PERIOD names can be memorised by using the word sentence read from bottom to top…… Note – mya: millions of years ago
EON
PERIOD
ERA
AGE
(mya)
Quizzically
___________zoic
___________zoic
2
Terribly
65
Creak
___________zoic
144
Joints
213
Their
248
Perhaps
___________zoic
286
MAJOR EVENTS
Carefully
360
Down
408
Sit
438
Often
505
Camels
545
___________zoic
2500
Pre ___________
Arch___________
Had ___________
4000
4600