The acidity levels of the early oceans were much lower than today, so it took 4 billion years of weathering in order to reach the level of salinity present in the oceans today.
Indicate whether this statement is true or false.
Q. 2 - Scientific knowledge of many events of the Precambrian is limited because ________.
A) metamorphism altered and deformed many rocks
B) plate tectonics consumed many of the oldest tectonic plates
C) many ancient rocks have been eroded
D) any ancient rocks have been covered by a mantle of sediments
E) metamorphism, plate tectonics, erosion, and sediments account for the limited knowledge of Precambrian events
Q. 3 - Most Precambrian rocks lack fossils, which makes correlating rock units over large distances difficult.
Indicate whether this statement is true or false.
Q. 4 - Stromatolites went extinct at the end of the Permian Period along with 95 percent of all marine species on Earth.
Indicate whether this statement is true or false.
Q. 5 - What is the molecular formula for ozone?
A) O
B) O2
C) O3
D) O4
Q. 6 - Which of the following gases was present in Earth's early atmosphere?
A) Water vapor
B) Carbon dioxide
C) Hydrogen
D) Methane
E) All of these gases
Q. 7 - Why is there virtually no hydrogen and helium present in the atmosphere today?
A) These gases were burned off by solar radiation.
B) The gravitational force of Earth was not strong enough to hold them.
C) These gases were consumed by rock-forming processes.
D) Acid rain removed these gases from the atmosphere.
Q. 8 - Which process is responsible for the oxygen in the atmosphere today?
A) Photosynthesis
B) Outgassing of volcanoes
C) Weathering of carbonate rocks
D) Asteroid impact
Quick Reply
