Chapter 1: An Introduction to Geology

Question 1

What is Geology?

Answer 1

the study of earth and its processes

Question 2

How can we, humans, influence geologic processes?

Answer 2

River flooding is natural, but the magnitude and frequency of flooding can be changed significantly by human activities such as clearing forests, building cities, and constructing dams.

The relationship between people and the natural environment
is an important focus of geology. This includes natural hazards,
resources, and human influences on geologic processes. Unfortunately, natural systems do not always adjust to artificial changes in ways that we can anticipate. Thus, an environmental alteration intended to benefit society sometimes has the opposite effec

Question 3

Differentiate catastrophism from uniformitarianism.

Answer 3

Catastrophism theorises that the Earth has largely been shaped by sudden, short-lived, violent events, such as floods, volcanoes, or earthquakes. Uniformitarianism suggests that the Earth has gradually changed by slow, continuous, and uniform processes, such as erosion, sedimentation, or plate tectonics.

Uniformitarianism, one of the fundamental principles of modern geology advanced by James Hutton in the late 1700s

Question 4

Describe law of superposition

Answer 4

The law of superposition is a principle of geology that states that in a sequence of sedimentary rock layers, the oldest layer is at the bottom and the youngest layer is at the top. This is because the older layers are buried by the newer ones over time. The law of superposition is used to determine the relative ages of rock strata. It was first observed and named by Friedrich von Schiller in 1785.

Question 5

Describe the principle of fossil succession

Answer 5

The principle of fossil succession is a law that states that fossils change in a predictable and consistent order through time and across different locations. This principle allows scientists to correlate rocks of the same age based on the fossils they contain, and to trace the evolution of animals and plants through geologic time. The principle is based on the observation that different fossils are unique to different strata of sedimentary rocks.

Question 6

The process by which scientists gather facts and formulate scientific hypotheses and theories.

Answer 6

Scientific Method

Question 7

How to determine what is occuring in the natural world?

Answer 7

(1) collect facts,
(2) ask questions and develop hypotheses that may answer these questions,
(3) develop observations and experiments to test the hypotheses, and
(4) accept, modify, or reject hypotheses on the basis of extensive testing.

Question 8

What are the three major physical enrivonment of the Earth?

Answer 8

the solid Earth, or geosphere; the water portion of our planet, the hydrosphere; and Earth’s gaseous envelope, the atmosphere. In addition, the biosphere, the totality of life on Earth, interacts with each of the three physical realms and is an equally integral part of Earth.

Question 9

What is a system?

Answer 9

A group of interacting parts that form a complex whole.

Question 10

Differentiate closed systems vs open systems

Answer 10

Open systems allow energy and mass to pass across the system boundary. A closed system allows energy but not mass across its system boundary. An isolated system allows neither mass nor energy to pass across the system boundary.

Question 11

What is positive feedback mechanism?

Answer 11

A positive feedback mechanism is a process in which the end products of an action cause more of that action to occur in a feedback loop. This amplifies the original action

Question 12

What is negative feedback mechanism?

Answer 12

A negative feedback mechanism is a type of regulation in biological systems in which the end product of a process reduces the stimulus of that same process. This type of feedback is present in many biological reactions and allows the body to control various aspects of its internal environment. Negative feedback occurs when the product of a pathway turns the biochemical pathway off.

Question 13

List the sources of energy that power the Earth systems.

Answer 13

Based on the book: The two sources of energy that power the Earth system are (1) the Sun, which drives the external processes that occur in the atmosphere, hydrosphere, and at Earth’s surface, and (2) heat from Earth’s interior that powers the internal processes that produce volcanoes, earthquakes, and mountains.

However, there are additions to the list which is the heat from the decay of radioactive elements and heat from when the planet was formed and accreted .

Question 14

Explain the process of rock cycle.

Answer 14

The rock cycle is one of the many cycles or loops of the Earth system in which matter is recycled. The rock cycle is a means of viewing many of the interrelationships of geology. It illustrates the origin of the three basic rock groups and the role of various geologic processes in transforming one rock type into another.

Question 15

What is relative dating?

Answer 15

the placing of events in their proper sequence or order without knowing their age in years, scientists developed a geologic time scale during the 19th century. Relative dates can be established by applying such principles as the law of superposition and the principle of fossil succession.

Question 16

Describe the nebular theory?

Answer 16

The nebular theory is an explanation for the formation of solar systems, which suggests that stars are born from clouds of interstellar gas and dust. The theory holds that the solar system formed from the gravitational collapse of a great, giant cloud of gas and dust.

The widely accepted modern variant of the nebular theory is the ** solar nebular disk model (SNDM) or solar nebular model**. The theory explains the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun’s rotation. According to the nebular theory, stars form in massive and dense clouds of molecular hydrogen. The theory is widely accepted by scientists today because of its success in explaining the major characteristics of our solar system.

Question 17

What are the Earth’s internal structures?

Answer 17

Earth’s internal structure is divided into layers based on differences in chemical composition and on the basis of changes in physical properties. Compositionally, Earth is divided into a thin outer crust, a solid rocky mantle, and a dense core. Other layers, based on physical properties, include the lithosphere, asthenosphere, lower mantle, outer core, and inner core

Question 18

What are the two divisions of Earth’s Surface?

Answer 18

Two principal divisions of Earth’s surface are the continents and ocean basins. A significant difference is their relative levels. The elevation differences between continents and ocean basins is primarily the result of differences in their respective densities and thicknesses.

Question 19

Explain the three distinct types of plate boundaries.

Answer 19

1. Convergent boundaries - A convergent boundary is a place where two or more tectonic plates move towards each other and collide.
2. Divergent boundaries -
3. Transform fault boundaries -

A subducting plate’s path (called the Benioff-Wadati [or Wadati-Benioff] zone) is defined by numerous earthquakes along a plane that is typically inclined between 30° and 60° into the mantle. The frequency of earthquakes in these areas is due to the convergence and subduction of tectonic plates

Question 20

What is the theory of plate tectonics?

Answer 20

Plate tectonics is a scientific theory that explains how major landforms are created as a result of Earth’s subterranean movements.

In plate tectonics, Earth’s outermost layer, or lithosphere—made up of the crust and upper mantle—is broken into large rocky plates. These plates lie on top of a partially molten layer of rock called the asthenosphere. Due to the convection of the asthenosphere and lithosphere, the plates move relative to each other at different rates, from two to 15 centimeters (one to six inches) per year.

Question 21

The largest features of the continents can be divided into two categories:

Answer 21

mountain belts and stable interiors

Question 22

The ocean floor is divided into three major topographic units:

Answer 22

continental margins, deep ocean-basins, and ocean (mid-oceanic) ridges

Question 23

Most volcanoes are found above subduction zones, but some form far away from these plate boundaries. How could this be explained?

Answer 23

This question was finally answered in 1963 by a Canadian geologist, John Tuzo Wilson. He proposed that volcanic island chains, like the Hawaiian Islands, are created by fixed “hot spots” in the mantle. At those places, magma forces its way upward through the moving plate of the sea floor. As the plate moves over the hot spot, one volcanic island after another is formed.

Wilson’s explanation gave further support to plate tectonics. Today, the theory is almost universally accepted.

Question 24

What are the Wadati-Benioff zones in the Philippines?

Answer 24

The most significant subduction zone, the Manila Trench subduction zone, is a 1,000 km-long zone between Taiwan and Mindoro Island in the Philippines. It is characterized by an east-dipping Wadati-Benioff zone that extends to ~200 km depth (Hamburger et al., 1983).