GEOL 101 Section 004 Text Essentials of Geology

GEOL 101 Section 004 • Text: Essentials of Geology, by Marshak • You must take the lab, and pass it, to pass this course. • Labs do meet this week. If you already missed your lab: http: //www. agiweb. org/workforce/video/index. html • Grades – calculated as on syllabus. • Grades posted on My. UNLV: http: //aboutmyunlv. edu/ • Department and UNLV classroom policies – participation (quizzes), attendance (no makeup exams), misconduct and the learning environment (laptops, cellphones, etc. ), administrative drops, children, etc… • How to succeed in this class?

For Powerpoint Lectures: http: //geoscience. unlv. edu/terrylspell. htm Click on “GEOL 101…” under Teaching

What is Geology? • Geology = Geo (Earth) and Logia (study or science). • Geoscience perhaps a more modern term. • Geology is a science of it’s own, but it also includes chemistry, physics, math, biology, engineering, economics and more. • There are many areas of study in geology and they are so diverse that one geologist may not know much about what another is doing.

Examples of Different Areas of Geology • Volcanology – study of volcanoes • Geochronology – study of the age of rocks • Geophysics – study of earthquakes and the interior of the Earth • Paleontology – study of fossils and evolution of life • Structural Geology – study of how rocks deform, e. g. during mountain building events • Hydrology – study of surface and ground water • Petroleum and Mining Geology – study of petroleum, natural gas and ore (metal) deposits

Why Study Geology? • Understanding Volcanic Eruptions: • In 1883, the biggest explosion the inhabited world has ever known occurred. Indonesia's Krakatoa volcano erupted. It did so with the force of 13, 000 Hiroshima atom bombs, propelled a trillion cubic feet of rock, pumice and ash into the air, and made a noise loud enough to be heard 1, 930 miles away in Perth. The explosions, fallout and resulting tsunami (130 feet high in places) killed 36, 417 people in Java and Sumatra, destroyed 165 villages and towns, and two-thirds of the island. Wind streams blew the fine ash as far away as New York; sea levels were raised in the English Channel, and over the following year, global temperatures were reduced by 1. 2 o. C. • Krakatoa was a relatively small eruption! (~17 km 3 erupted magma)

Jemez Volcanic Field, west-central U. S.

Ash layers 2 cm thick found in drillcores in the Atlantic ocean. 1. 85 Ma – 15 km 3 1. 65 Ma – 400 km 3 1. 22 Ma – 250 km 3 60 ka – 2 km 3

Mt. Ranier Looms Ominously Over The Seattle Area….

How would you like to wake up and see this out your window? What do we know about predicting such events? Eruption Over Santiago, Chile

Why study Geology? • Earth interacts with humanity via: – Earthquakes – Floods – Volcanoes – Landslides

Why study Geology? • Earth materials are the source of most energy used on the planet. – – Petroleum Natural gas Coal Uranium

Why study Geology? Is our use of fossil fuels the cause?

Why study Geology? • Earth’s surface is covered with soil that supports natural and agricultural plants. • Soil is made largely of decomposed rock. Fig 1. 2 c

Basic vs Applied Geologic Research • Basic research is curiosity driven, plain and simple, we just want to know. Example: How did a metallic ore deposit form? • Applied research is need driven only. Example: How do we find metallic ore deposits? The two are not completely disconnected. Someone studying how ore deposits form (basic research) may discover that they form by processes occurring only in specific places on Earth. Thus, someone wanting to know how to find them (applied research) will benefit… and perhaps get rich!

What are rates of geologic processes? Fig 1. 4 This figure shows the difference in the rates of Earth processes as compared to processes we can normally observe. Some Earth processes are fast, but most are… very slow. Many important processes are much slower than fingernail growth. Must remember geologic time, millions and billions of years are available.

Changes in Geology – Past 100 years • Geology began as an observational science. • Geologists looked at the Earth and tried to explain what they saw. • Analytical instruments began to be rapidly developed in the early 1900’s. • By 1950’s we basically had the instruments we have today, but they have been continually refined and developed. • Past 10 -20 years have seen dramatic new developments in analytical capabilities. • Result is that geology has become an analytically based science, laboratory data is very important.

Piston-cylinder device used to reproduce T and P in the deep Earth Ion Microprobe used for U-Pb dating

Scientific Method?

Scientific Method? A Continuous, Dynamic Process

Geologists use the Scientific Method 1) Make observations, collect data. 2) Develop idea(s) to explain what is seen, this is a hypothesis. 3) Come up with ways to test the hypothesis. 4) If well designed the test(s) will validate, or refute, the hypothesis. 5) A hypothesis that has been tested repeatedly, often for many years, and has continued to be supported as new data becomes available, is called a theory.

Scientific Method ? ? ? You are driving home when suddenly… your car stops running.

1) Observations – collect data (information) • Car sputtered to a stop • Starter cranks engine over, but car won’t run • Gas gauge sitting on empty

2) Hypothesis – idea(s) • Your car is out of gas ($10 fix). • You need a new engine ($1000 fix).

3) Test Hypothesis – by prediction and experiment • Put some gas in the tank, if out of gas then it should now run. • Take car to shop and have new engine installed, if engine was bad it should now run. • Which would you do first? (Occam’s Razor)

4) Accept or reject hypothesis • Car runs after gas is put into tank – accept they hypothesis that it was out of gas. • Car does not run after gas put into tank – reject hypothesis that it was out of gas. • Return to step 2 (different hypothesis) or perhaps even step 1 (more observations).

5) Theory • You are not a genius, and forget to put gas in the car every week. • The car quits running on the way home at the end of each week. This happens over and over… • Putting gas in the tank always fixes the problem. • Your theory? Whenever the car quits running it needs gas. • A theory is a hypothesis that has not yet been proven wrong – one day your car may truly need a new engine instead of gas!

Next: Formation and Structure of the Earth