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Everyday Geology

Mars Close Approach
Mars made its closest approach to Earth in over 60,000 years last week. Why does Mars capture the attention of scientists and other people so much?
Book Review of Krakatoa, The Day the World Exploded August 27, 1883
A review of the book by Simon Winchester.
Seafloor Spreading, Part 2
The theory of seafloor spreading required many pieces of evidence to convince a highly skeptical audience. In the end Harry Hess and others found four primary keys that helped shape the theory.
Seafloor Spreading, Part 1
A revolution spread through the science of geology in the 1960’s and culminated in the theory of plate tectonics. The theory was supported by key research conducted in and under the world’s oceans that led to the idea of seafloor spreading.
Magnetic Sampling and Analysis
Sampling and analysis of rocks for their magnetic properties is a complicated and tedious process. The results though, have helped to revolutionize the science of geology.
Rock Magnetism
Plate Tectonic theory revolutionized the science of geology. The study of magnetism in rocks was one of the keys that led to this grand unifying theory of geology.
Snowball Earth: A Review of the Book by Gabrielle Walker
My review of the new book on the controversial Snowball Earth theory written by Gabrielle Walker.
Snowball Earth Part 3: Evidence Against
Was the Earth covered in a globe-spanning ice age? Some researchers say the evidence suggests no, and argue for a less dramatic “Slushball Earth” theory.
Snowball Earth Part 2: The Evidence For
Imagine the Earth gripped in a world-spanning ice age lasting millions of years? Science fiction? Maybe not. Part 2 of our look at the evidence for a "Snowball Earth".
Snowball Earth
Imagine the Earth gripped in a world-spanning ice age lasting millions of years? Science fiction? Maybe not. A look at the evidence for a "Snowball Earth".
Visit to Devil's Cave.
Description of my visit to Teufelshöhle, or Devil's Cave, in Pottenstein, Germany.
Alfred Wegener and Continental Drift
The modern theory of Plate Tectonics owes much to the early work of Alfred Wegener. Wegener's work on Continental Drift was met with ridicule and attacked by the geologic community but was eventually vindicated by later research.
Earthquakes: Probabilities and Hazards
Do you need to worry about an earthquake where you live? How do scientists measure these risks and what does it mean for you?
Earthquake Preparedness: Are you prepared?
90% of Americans live in seismically active areas. Are you prepared should an earthquake occur where you live? Learn some tips and some important links for preparing for an earthquake.
National Petroleum Reserve, Alaska
A brief history and overview of the most recent USGS assessment of the National Petroleum Reserve, Alaska.
Metamorphic Rocks: Types and Facies
Understanding the main types of metamorphism and the facies concept help round out or knowledge of metamorphic rocks.
Classification of Metamorphic Rocks
Affected by wide ranges of temperature and pressure, metamorphic rocks are often the most difficult of rocks to identify. The naming process can be simplified by keeping two things in mind, texture and mineralogy.
Controlling Factors of Metamorphic Rocks
To begin to classify metamorphic rocks one must first understand the different controlling factors that work to create them.
Book Review: Roadside Geology of Massachusetts
Review of the book, written by James W. Skehan.
Review of the Sam Noble Oklahoma Museum of Natural History
An overview of the Sam Noble Oklahoma Museum, located on the campus of the University of Oklahoma.
Mass Wasting 2
We hear the word landslide used quite often in the press, but landslides can occur in differnt ways and at different speeds. Learn about the different types of landslides that affect our lives.
Mass Wasting
Landslides cause over a billion dollars in damage each year in the United States. The more geologists study how landslides occur, the more we can reduce the dangers they pose.
Glacial Deposits
How do we know where glaciers have been? Evidence of a glaciers passing is found in the rocks they carry along and leave behind when they retreat.
Glacial Lake Missoula: Book Review of Glacial Lake Missoula and its Humongous Floods
A review of the book written by David Alt.
Ice Ages
With recent discussions in the press concerning Global Warming, El Nino, and other climatic changes it is often forgotten that until around 10,000 years ago, large continent spanning ice sheets covered much of the Earth.
Caves and Caverns
Groundwater plays an important role in creating the spectacular caves and caverns found throughout the world. How do caves form and what are the features that amaze and astound us?
Groundwater
Most of the fresh water used in communities is found underground, nearly 60 times as plentiful as the water found in lakes and rivers. Groundwater is a valuable and important resource across the globe.
Geology Destinations: Great Smoky Mountain National Park
Overview of the geology of the most visited national park in the nation, Great Smoky Mountain National Park.
The Hydrologic Cycle
Rain falls and rivers flow, but where does the water go and how does it become rain in the first place? The Hydrologic Cycle gives us the answer.
Carbonate Rock Classification
Carbonate rocks are classified based on the types of particles that compose the rock, and the matrix that holds these particles together.
National Museum of Natural History
Overview of the Smithsonian Institutions National Museum of Natural History located in Washington, DC.
Book Review: The Map that Changed the World
A review of the book by Simon Winchester.
Sandstone Classification
Once we can describe a sandstone in the field we need to give it a name. Find out how to name a sandstone in three easy steps.
Sandstones and Conglomerates
It takes a bit more than recognizing a rock is a sandstone to accurately describe it in the field.
Mudrocks
The most abundant type of rock on the Earth, but also the most difficult to classify. Learn about some simple ways to tell your claystone from your mudstone.
Introduction to Sedimentary Rocks
The most abundant type of rock on the Earth are the sedimentary rocks. Why is this so, and what are they?
Native Elements
Explore the world of the native elements. Their rarity and uses make them some of the most important minerals in the world.
Weathering Part 2: Chemical Weathering
The agents of weathering are powerful forces, working to breakdown the rock around us. None of these agents are more powerful those that chemically affect the rocks.
Weathering Part 1: Physical Weathering
What is the most destructive force in nature? Earthquakes, volcanoes, hurricanes, or the humble raindrop?
Mineralogy 101: Crystal Systems
Nearly every mineral can be assigned to one of six different crystal systems.
Mineralogy 101: Crystals
A look at the structure of crystals, and how this affects the types of minerals that are formed.
Geology Year End Review
A look back on geology events of 2001.
Yellowstone National Park, Part 3
More than volcanism has shaped the Yellowstone we see today. Ice, in the form of glaciers, has sculpted and carved the landscape to what we see today.
Yellowstone National Park, Part 2
The star attraction of Yellowstone is the geysers. But what is a geyser, and how do they work?
Yellowstone National Park, Part 1
Yellowstone National Park is a product of its geology. Without the geological processes that shaped it, Yellowstone would be another mountain range.
Visit the Museum of the Rockies
The next time you are in southern Montana, take an afternoon to visit Bozeman, and the Museum of the Rockies.
Holiday Gift Ideas
Looking for the perfect gift gor the geologist in your life? Read on for some rockin' ideas.
Igneous Rock Identification (Advanced)
More detailed diagrams to help you in identifying igneous rocks.
Igneous Rock Identification (Basic)
A basic key to get you started on identification of igneous rocks.
Bowen's Reaction Series
How does magma become the igneous rocks we see? Norman Bowen identified one possible method for the evolution of magmas.
Earth's Interior
What we see of the Earth at the surface is compossed of less than one percent of the Earth's mass. Over 99 percent of the Earth's mass will never be seen or physically studied by geologists. Despite this, geologists know quite a lot about the Earths interior.
Igneous Intrusive Bodies
Magma rising from the Earth's interior isn't an indistinct blob, but takes on distinct shapes. Depending on the composition of the igneous rock, and the overlying geology there are several shapes an intruding igneous body can take
Smoking Gun for the Permian Extinction?
New geological evidence now supports the theory that a very large (possibly 60 km in size) asteroid collided with the earth at the end of the Permian period. This impact was probably the leading cause for the extinction of nearly all life on earth at the end of the Permian.
Arctic National Wildlife Refuge - Part 3
The entire area along Alaska’s North Slope is a delicately balanced ecosystem. Is it possible to explore, develop and produce a large oil field without seriously impacting the wildlife? The oil companies feel they can.
Arctic National Wildlife Refuge - Part 2
The potential dangers associated with oil exploration and drilling are a threat to the delicately balanced ecosystem of the refuge. Should we allow the destruction of a pristine wilderness for the sake of a few million barrels of oil?
Arctic National Wildlife Refuge Part 1
Looking at the facts about ANWR. How much oil is there and is it worth it to get it out of the ground?
Petroleum 3 - How do they get it out of the ground?
We know how oil is formed, and we know how geologists search for petroleum deposits. But how do the oil companies get the oil out of the ground?
Petroleum 2: How do they know where to drill?
Knowing how the petroleum is formed is only the first step. How do geologists know where to dig the wells that get the petroleum out of the ground
Petroleum 1: How oil becomes oil.
We use it everyday, to cook with, power our automobiles, and run our power plants. But do you really know where the oil and gas we use comes from? Take a look at how oil becomes oil.
Book review: No Apparent Danger
Review of the book, No Apparent Danger by Victoria Bruce that looks at the volcanic disasters at Galeras and Nevado del Ruiz in Columbia
New Mexico Museum of Natural History & Science
The New Mexico Museum of Natural History & Science is located in historic Old Town in Albuquerque New Mexico. The natural history museum has been one of my favorite museums ever since I first visited it in 1987.
How to take good field notes.
The taking and recording of field notes is one of the most important things a geologist does when in the field. Without well written and well understood notes, further interpretation of the rocks being studied may not be possible.
Everything a geologist needs to be successful in the field.
Going into the field is not a simple undertaking. It takes time to prepare for a field trip, to plan and organize the trip, even if it's across town. The geologist must have the right tools and equipment. Read on to see what it takes to be a successful field geologist.
Absolute Time 2
Radiometric dating is a complex method for dating the rocks of the earth. There are only a few types of rock that can be dated, and potential problems that need to be avoided to give an accurate date for the rock sample.
Absolute Time 1
Through research, physicists and geologists have determined that certain isotopes of elements will decay into new elements. Using the decay rate, and knowing the half-life of the isotope, a geologist can date a sample of rock and determine its age.
Relative Time
Geologists can use several principles to help relate the sequence of events to determine the relative time scale for a particular sequence of rocks. Understanding these principles helps a geologist place the rocks within the confines of the geologic time scale.
Geologic Time
You may be familiar with the concept of time, but you have never experienced time as a geologist does. Learn about geologic time and prepare yourself to think in terms of "deep time".
Volcanoes
Volcanoes have always fascinated us, and have been a source of destruction and a source of growth. In this article I will explore the four main types of volcanoes and the differences and potential hazard from each.
Understanding Time and Rock Units in Geology
Geologists use three different units to help in their study of the history of the earth. Time units represent the continuous flow of time through geologic history, rock units represent the different lithologies found across the globe, and time-rock units represent all the rocks formed worldwide during a specific period of geologic time. This week we will examine these units and how they relate to each other.
Unconformities
Unconformities are an important part of the stratigraphic record. They represent periods of non-deposition and erosion. Knowing how to interpret and identify unconformities can help a geologist piece together the history of the stratigraphic record, and how that sequence of rocks relates to other sequences.
Stratigraphy
The science of stratigraphy is important for the information it tells us about the rock record and how those rocks were originally deposited. The laws and principles set forth by early scientists help modern stratigraphers to know how sediment was originally deposited, to know which rock is older, and how to use fossils to help link different rock units to the same geologic time.
Earthquakes
We have all probably seen the results from earthquakes, and many of us have experienced an earthquake as it occurred. But how do geologists know where and earthquake was centered and how strong it was? This article will look at earthquakes in detail.
Faults
The earth is a dynamic system and has been know to move suddenly from time to time. Learn about the different types of faults, the reasons we have earthquakes. Just remember when you feel the earth rumble - it's not my fault
Strike and Dip
Strike and dip are important for identifying and orientating geologic structures in the field. Understanding what strike and dip are, and how to measure them in the field are important skills for a geologist to learn.
Folded Rocks
Great forces are applied to the rocks of the earth. In places, these forces cause the rocks to fracture and break. Other times, the rocks bend and form folds
Mineral Identification
Minerals have always fascinated people, whether from a finely cut diamond or panning for gold. But how do geologist know what to call the different minerals they find? This article explores several of the common tests used by geologists to help them identify minerals.
Metamorphic Rocks
Not all rocks occur from volcanoes, or from the deposition of sediment. Our last category of rocks from the rock cycle are those rocks that have been altered in the earth by high heat and/or pressure - Metamorphic Rocks.
Igneous Rocks
The next area of the rock cycle we will look at are those rocks that are formed from the fiery interior of the earth. Igneous rocks are those rocks that form from hot magma erupting from volcanoes or slowly intruding into the subsurface.
Sedimentary Rocks
The majority of the rocks that make up our world are sedimentary in nature. Learn about the different types of sedimentary rocks, the first stop in our understanding of the rock cycle.
The Rock Cycle
An understanding of geology requires us to learn how the rocks around us are formed. Learning how all the rocks we see are part of a larger cycle is the first step in understanding geology.
Geology as a Career
Ever wondered what a geologist does? Check out a few of the career opportunities available to geologists.
An Introduction to Geology
An introduction to the science of geology. What does a geologist do and what does a person need to become a geologist.