Chapter One

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Chapter One: Introduction to Physical Geology and the Environment
WHAT IS GEOLOGY?
Geology geo and logos “the study of the earth
First known geological map created by Egyptians over 3000 years ago
Geology: The scientific study of the Earth
Industrial Revolution in northern Europe created a growing demand for energy and minerals (coal,
limestone, iron and water)
One of the earliest detailed geologic maps was published in England in 1815 by William Smith
(Father of English Geology)
Mid 19th century geological mapping began in North America driven by the need to locate
resources for an expanding population
Sir William Logan 1842 founding director of the Geological Survey of Canada first to
systematically describe the geology of Canada
Geologists have gathered and interpreted many data from the continents and ocean floors and
have built a fairly detailed picture of the Earth’s structures and processes; they have also gained
understanding of the vast age of the planet
Late 17th century Earth was believed to be 6000 years old
Now Earth is believed to be at least 4500 million years old
Moving Continents
Alfred Wegener suggest the movement of continents; wrote in 1912 about continental drift;
recognized that today’s continents had been clustered together previously in a large land mass
that moved apart (Pangea: Greek for “all the lands”)
Took many years of studying data from oceans and the margins of continents for geoscientists to
demonstrate that continents move. This allowed for the development of the plate tectonics
theory. Canadian geophysicist, J.Tuzo Wilson (1970s) brought together several key elements of
the plate tectonics theory
William Smith (1769 1839)
From the village of Churchill in Oxfordshire
Took notes on his observations during his travels through the country
1793 conducted surveys for the excavation of a canal in Bath; noted the regular succession of
the rock layers
1799 outlined and coloured the distribution of geological features on a map of the local area
around Bath
Produced the first comprehensive geological map of England in 1815
Widely recognized as one of the founders of geology
Sir William Logan
Canada’s premier scientist
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His geological maps of South Wales were revolutionary In that they introduced the cross section, a
hypothetical vertical slice through the land
Travelled on foot across Canada, generating full scientific descriptions of rocks, soil and minerals
Created the first systematic layout of the geology of Canada
Discovered several ore bodies
Credited with the initial suggestion that coal is an organic deposit
Canada’s highest mountain (Mount Logan) in the Yukon is named after him
Alfred Wegener (1880 1930)
A German meteorologist who first suggested the theory of continental drift
Proposed a supercontinent called Pangea
Evidence of continental drift: geographic fit of South America and Africa, and similarities of rock
types, structures, and fossils on now widely separated continents
His ideas were discredited by most until the 1960s, when the identification of mid-ocean ridges
and paleomagnetic data provided a mechanism for the movement of continents
Time and Geology
Some geological processes (great landslide or volcanic eruption) occur quickly when stored energy
is suddenly released
However, most geological processes are slow but relentless, reflecting the pace at which Earth`s
processes work
The rate of plate motion is relatively fast. If new magma erupts and solidifies along a mid-oceanic
ridge (underwater mountain range), at the rate of 1cm per year, it will take 100 million years for
the currently forming part of the crust to travel 1000 km.
Earth is estimated to be at least 4.55 billion years old
Fossils indicate that complex forms of animal life have existed for about 545 million years
Reptiles became abundant about 230 million ears ago
Dinosaurs evolved from reptiles and became extinct about 65 million years ago
Humans have been here for the last 3 million years
J. Tuzo Wilson (1908 1993)
First Canadian to complete a degree in geophysics at UofT
Remembered for contributions to the plate tectonics theory (particularly with transform faults
and hot spots)
Showed that the shield was composed of a mosaic of lerranes? Separated by long linear features
interpreted as ancient fault lines
Recognized large scale faults on modern ocean floors that offset the crust laterally but neither
created nor destroyed material
First to recognize the significance of young volcanic islands stuck in the middle of oceans
Suggested that volcanic island chains, such as Hawaii, resulted from a moving plate drifting over a
stationary magma plume in the mantle
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He called these active volcanoes “hot spots”
WHAT DO GEOSCIENTISTS DO?
In the past, they spent most of their time looking for signs of minerals
These prospectors are now called exploration geologists
o They look for gold, silver, diamonds, etc
o Move around in four wheel drive trucks/helicopters
Geoscientists:
Geochemists are comfortable working in the lab and use high tech equipment to analyze the
chemistry of rocks or minerals. They consult with mineralogists who study minerals, or
petrologists who study the makeup of rocks and how they form
Other geoscientists employ high tech equipment using boats, planes, or satellites to learn more of
the nature of the physical conditions on or under the Earth’s surface: these are called
geophysicists. Similar techniques used by petroleum geophysicists in their search for oil and gas or
by coal geologists. Seismologists study how to measure and mitigate earthquake activity. A
paleontologist is a specialist who studies the fossilized remains of ancient organisms
Much of Canada’s landscape is made of landforms and sediments left behind from when ice
sheets covered the northern part of North America. These landforms and sediments are studied
by glacial geologists. Such sediments contain and transmit water, an increasingly important
mineral that is studied and protected by hydrogeologists.
A day in the life of an Exploration and Mining Geoscientist
Aim is to find gold in the Canadian Shield
Gold can be found in volcanic rocks, quartz veins, and where rocks have been stretched along
faults
A day in the life of a Petroleum Geoscientist
Uses core descriptions to interpret the depositional environments in which the rocks formed and
to begin to piece together the geological history of the rocks within and around the reservoir
Combines his analysis of rock characteristics with geophysical data such as seismic reflection and
downhole geophysical well logs to build up a picture of the subsurface extent of porous reservoir
rocks
He reconstructs the 3D architecture of reservoirs using subsurface modelling programs
Environmental Geology: New Challenges for Geoscientists
The new challenges for today’s geoscientist relate to the finding and managing of drinking water
(mostly groundwater), and in dealing with a wide variety of wastes ranging from radioactive waste
to household (municipal) waste. These are dealt with by environmental geoscientists
Real estate and insurance businesses employ environmental geoscientists to provide key info
regarding past use of lands and buildings as part of the due diligence process.
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