Engineering Geology ECIV 3302site.iugaza.edu.ps/jhamad/files/2018/09/chapter-1Geo-p-2019.pdf ·...

Engineering Geology ECIV 3302

Chapter (1) Introduction

Instructor : Dr. Jehad Hamad

2019/2018 September 17, 2018ECIV 3302 Engineering Geology Civil Engr. Dept.1

September 17, 2018ECIV 3302 Engineering Geology Civil Engr. Dept.2

Essentials Of

GeologyBy

FredeRick R. LutgensEdward J. TarBuck

Eleventh Edition

Chapter 1:

Introduction to Earth Science

ECIV 3302 Engineering Geology Civil Engr. Dept.

3September 17, 2018

Introduction to Geology

Geology is the study of the Earth, "Geo" means earth and "ogly" means science. It is divided into physical and historical geology.

1.Physical geology :examines the materials composing the Earth and seeks to

understand the processes that operate beneath and upon the surface.

2. Historical Geology:examines the origin of the Earth and the development of the

planet through its 4.6 billion years history. It deals with the layered rock record and fossils

September 17, 2018 ECIV 3302 Engineering Geology Civil Engr. Dept.

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Geology SubdivisionsAcademic – earth history and fundamental processesMineralogy, Petrology – Rocks, mineral and origins Stratigraphy – classification and definition of beds (sedimentary) Structure/Tectonics – earth structure and origins Geochemistry GeophysicsApplied – applications to specific industries, engineering and environment Petroleum Geology/Geophysics Economic Geology (Minerals) Environmental Geology (geophysics, geochemistry) Hydrogeology Engineering Geology (geophysics, geochemistry)

Earth science is the name for all the sciences that collectively seek to

understand Earth and its neighbors in space.


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It includes geology, oceanography, meteorology, and astronomy.


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Geology is traditionally divided into two broad areas—physical and historical.


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Environment:refers to everything that surrounds and influences an organism.


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These influences can be biological, social, or physical.


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When applied to Earth science today, the term environmental is usually reserved

for those aspects that focus on the relationships between people and the

natural environment.


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Resources: are an important environmental concern


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The two broad categories of resources are (1) renewable, which means that they can be replenished over relatively short time

spans, and (2) nonrenewable.


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As population grows, the demand for resources expands as well.


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Environmental problems can be local, regional, or global.


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Human-induced problems include - Urban Air Pollution, Acid Rain, Ozone Depletion,

and Global Warming.


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Natural hazards include earthquakes, landslides, floods, and hurricanes.


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As world population grows, pressures on the environment also increase.


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All science is based on the assumption that the natural world behaves in a consistent

and predictable manner.


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The process by which scientists gather facts through observation and careful

measurement and formulate scientific hypotheses and theories is called the

scientific method.


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To determine what is occurring in the natural world, scientists often (1) collect facts,(2) develop a scientific hypothesis, (3) construct experiments to validate the hypothesis, and (4) accept, modify, or reject the hypothesis on the basis of extensive testing.


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Other discoveries represent purely theoretical ideas that have stood up to

extensive examination.


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Still other scientific advancements have been made when a totally unexpected

happening occurred during an experiment.


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One of the challenges for those who study Earth is the great variety of space and

time scales.


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The geologic time scale subdivides the 4.5 billion years of Earth history into various

units.


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The Nebular hypothesis describes the formation of the solar system.


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The planets and Sun began forming about 5 billion years ago from a large cloud of

dust and gases.


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As the cloud contracted, it began to rotate and assume a disk shape.


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Material that was gravitationally pulled toward the center became the protosun.


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Within the rotating disk, small centers, called protoplanets, swept up more and more of

the cloud's debris.


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Because of their high temperatures and weak gravitational fields, the inner

planets were unable to accumulate and retain many of the lighter components.


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Because of the very cold temperatures existing far from the Sun, the large outer

planets consist of huge amounts of lighter materials.


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These gaseous substances account for the comparatively large sizes and low

densities of the outer planets.


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Earth's physical environment is traditionally divided into three major parts: the solid Earth or geosphere; the water portion of our planet,

the hydrosphere; and Earth's gaseous envelope, the atmosphere.


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In addition, the biosphere, the totality of life on Earth, interacts with each of the three

physical spheres and is an equally integral part of Earth.


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Earth's internal structure is divided into layers based on differences in chemical

composition and on the basis of changes in physical properties.


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Compositionally, Earth is divided into a thin outer crust, a solid rocky mantle, and a

dense core.


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Based on physical properties, the layers of Earth are


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(1) the lithosphere—the cool, rigid outermost layer that averages about 100 kilometers

thick,


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(2) the asthenosphere, a relatively weak layer located in the mantle beneath the

lithosphere,


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(3) the more rigid lower mantle, where rocks are very hot and capable of very gradual

flow,


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(4) the liquid outer core, where Earth's magnetic field is generated, and


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(5) the solid inner core.


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The lithosphere (sphere of rock): the cool, rigid outermost layer that average about 100 km thick, it extends to 100 km.

The asthenosphere (weak sphere), a relatively soft, weak layer located in the mantle beneath the lithosphere. It extends to about 660 km. The top portion of the asthenosphere has a temperature pressure regime that results it a small amount of melting. Within this weak zone , lithosphere is mechanically detached from the layer below. The result is that the lithosphere is able to move independently of the asthenosphere.

3. The more rigid mesosphere (between 660 to 2900 Km.) (lower mantle) where rocks are very hot and capable of gradual flow


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A view of EarthThere are Four Earth Spheres1. HydrosphereIt is the dynamic mass of water that is on the move, evaporating from the oceans to the atmosphere, precipitating back to the land, and running back to the ocean again.1. The oceans cover 71% of the earth's surface.2. The oceans account for 97% of the Earth's water.3. Only 3% of the Earth's water is considered fresh water(potential drinking water).


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2. Atmosphere

Earth is surrounded by a life giving gaseous envelope. It is very thin compared to the Earth's diameter (21 km) and it provides us with the air we breathe and protects us from the sun's heat and UV radiation.


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3. Biosphere

It includes all life on Earth and is concentrated near the surface in a zone that extends from the ocean floor upward for several kilometers into the atmosphere. Plants and animals depend on the physical environment for the basics of life.

Two principal divisions of Earth's surface are the continents and ocean basins.


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A significant difference is their relative levels.


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The elevation differences between continents and ocean basins is primarily

the result of differences in their respective densities and thicknesses.


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

belts and the stable interior.


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The ocean floor is divided into three major topographic units: continental margins, deep-ocean basins, and oceanic ridges.


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Although each of Earth's four spheres can be studied separately, they are all related

in a complex and continuously interacting whole that we call the Earth

system.


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Earth system science uses an interdisciplinary approach to integrate

the knowledge of several academic fields in the study of our planet and its global

environmental problems.


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A system is a group of interacting parts that form a complex whole.


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Closed systems are those in which energy moves freely in and out, but matter does

not enter or leave the system.


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In an open system, both energy and matter flow into and out of the system.


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The two sources of energy that power the Earth system are


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(1) the Sun, which drives the external processes that occur in the atmosphere, hydrosphere, and at Earth's surface, and


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(2) heat from Earth's interior, which powers the internal processes that produce

volcanoes, earthquakes, and mountains.


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(2) heat from Earth's interior, which powers the internal processes that produce

volcanoes, earthquakes, and mountains.


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Engineering Geology ECIV 3302site.iugaza.edu.ps/jhamad/files/2018/09/chapter-1Geo-p-2019.pdf ·...

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