Question 1

Which of the following statements is correct?

Accepted Answer

The lithosphere is the rigid outer layer of the Earth's surface, while the underlying asthenosphere is a weak and ductile region of the upper mantle. Therefore, the lithosphere is much stronger than the asthenosphere.

Question 2

Which of the following statements is correct?

Accepted Answer

The correct statement is C) climate system, plate tectonic system, and geodynamic system. These are recognized systems in Earth sciences that describe the climate interactions, the movement of Earth's plates, and the dynamics of Earth's interior, respectively.

Question 3

The geodynamo system is responsible for producing the Earth's

Accepted Answer

The geodynamo system is responsible for producing the Earth's magnetic field, which protects the planet from the solar wind and cosmic radiation. It is not directly responsible for the convecting mantle or weather.

Question 4

In the plate tectonic system, the lithospheric plates ride on the hot, weak ___ layer.

Accepted Answer

The asthenosphere is the hot, weak layer of the Earth's mantle that is beneath the lithospheric plates. The plates float on this layer and move due to the convection currents within the asthenosphere. The deep mantle and outer core are both lower layers of the Earth's interior and are not directly involved in plate tectonic movements.

Question 5

Which of the following rock types would be least likely to record the magnetic field at the time the rock formed?

Accepted Answer

Alluvial conglomerate is the least likely to record the magnetic field at the time the rock formed because it is a clastic sedimentary rock composed of rounded fragments or clasts of pre-existing rocks. Unlike basaltic lava flows, which can record the Earth's magnetic field as they cool and solidify, conglomerates are formed from the cementation of older rock fragments and do not undergo the same process of recording the magnetic field.

Question 6

The Earth has had a magnetic field for the last ___ years.

Accepted Answer

Scientists believe that the Earth's magnetic field has been present for at least 3.5 billion years based on evidence found in ancient rocks. While there is some evidence of a magnetic field existing up to 5 million years ago, it is thought to have been sporadic and not as continuous as the present-day field. The idea that the Earth's magnetic field has been present for 1 billion years is unsupported by current scientific evidence.

Question 7

Which of the following statements is true?

Accepted Answer

The Earth's magnetic poles are inclined about 11° from its rotation axis. This is known as the magnetic inclination or magnetic dip.

Question 8

What is the lower mantle made up of?

Accepted Answer

The lower mantle is made up primarily of dense silicate minerals such as peridotite and magnesium-iron silicate.

Question 9

Humans have been on Earth for ___ of Earth's history.

Accepted Answer

Earth is estimated to be around 4.5 billion years old, and the earliest known human-like species, Homo habilis, emerged less than 2 million years ago. This means humans have only been on Earth for less than 1% of the planet's history.

Question 10

When did our solar system form?

Accepted Answer

Scientists believe that our solar system formed about 4.6 billion years ago from a giant cloud of gas and dust called the solar nebula.

Question 11

Evidence in the rock record shows that there have been ___ major extinction events during Earth's history.

Accepted Answer

The rock record shows evidence for five major extinction events, including the famous extinction of the dinosaurs at the end of the Cretaceous period. The other four major extinction events occurred in the Ordovician, Devonian, Permian, and Triassic periods.

Question 12

About when did the first animals evolve on Earth, according to current geological understanding?

Accepted Answer

According to current geological understanding, the first animals evolved on Earth around 600 million years ago, during the Ediacaran Period. This is known as the Cambrian explosion, a period of rapid diversification and evolution of animal life.

Question 13

About when are Homo sapiens thought to have evolved?

Accepted Answer

Homo sapiens are believed to have evolved around 200,000 years ago. This is based on fossil and genetic evidence, which place the origins of our species in Africa during the Middle Pleistocene period. The other options are not accurate: 6000 years ago is a timeframe based on religious beliefs, 10,000,000 years ago is too early for Homo sapiens, and 65,000,000 years ago is when dinosaurs went extinct.

Question 14

How did Earth's atmosphere become oxygenated?

Accepted Answer

The atmosphere became oxygenated through the photosynthesis performed by oxygen-producing organisms, such as cyanobacteria, which released oxygen as a waste product. This process began around 2.4 billion years ago and gradually increased the oxygen levels in the atmosphere over time.

Question 15

Geologic evidence indicates Earth's moon and core formed within about the first 100 million years of Earth history.

Accepted Answer

Geologic evidence shows that the formation of the moon occurred through a giant impact between a Mars-sized object and the early Earth, which occurred approximately 4.5 billion years ago, within the first 100 million years of Earth's history. Additionally, the formation of Earth's core likely also occurred during this period.

Question 16

Approximately when did the mass-extinction event that led to the demise of the dinosaurs occur?

Accepted Answer

The mass-extinction event that led to the demise of the dinosaurs occurred approximately 65 million years ago, which is best represented by choice D.

Question 17

Which class of animals rose to dominance after the extinction of the dinosaurs?

Accepted Answer

Mammals rose to dominance after the extinction of the dinosaurs. They were able to thrive and diversify in the absence of the giant reptiles that had previously occupied many ecological niches. This led to the evolution of many new mammalian species and the eventual development of modern mammal diversity.

Question 18

Earth's hydrosphere did not begin to form until at least 2 billion years ago.

Accepted Answer

This statement is false. The hydrosphere began to form almost as soon as Earth formed, around 4.6 billion years ago, as water molecules were present in the gases that made up the planet's atmosphere. The hydrosphere continued to develop through volcanic activity, meteor impacts, and the process of outgassing.

Question 19

About what percentage of species went extinct during the largest mass extinction in Earth history?

Accepted Answer

During the largest mass extinction in Earth history, known as the Permian-Triassic extinction, approximately 95% of all species on Earth went extinct.

Quiz 2: How We Study Earth

Which of the following statements is correct?

Which of the following statements is correct?

The geodynamo system is responsible for producing the Earth's

In the plate tectonic system, the lithospheric plates ride on the hot, weak ___ layer.

Which of the following rock types would be least likely to record the magnetic field at the time the rock formed?

The Earth has had a magnetic field for the last ___ years.

Which of the following statements is true?

What is the lower mantle made up of?

Humans have been on Earth for ___ of Earth's history.

When did our solar system form?

Evidence in the rock record shows that there have been ___ major extinction events during Earth's history.

About when did the first animals evolve on Earth, according to current geological understanding?

About when are Homo sapiens thought to have evolved?

How did Earth's atmosphere become oxygenated?

Geologic evidence indicates Earth's moon and core formed within about the first 100 million years of Earth history.

Approximately when did the mass-extinction event that led to the demise of the dinosaurs occur?

Which class of animals rose to dominance after the extinction of the dinosaurs?

Earth's hydrosphere did not begin to form until at least 2 billion years ago.

About what percentage of species went extinct during the largest mass extinction in Earth history?