Geo 101 Lab 1 Measurements and Measuring-4

.docx

School

Cochise County Community College District *

*We aren’t endorsed by this school

Course

101

Subject

Geology

Date

Dec 6, 2023

Type

docx

Pages

Uploaded by ChiefHawk384

Cochise Community College Geology 101 Instructor: J.Deakin Laboratory One Observing and measuring Earth Materials and Processes Objectives: 1. Know what the geologic record is and how it is similar yet different from a book. 2. Know that Geology is based on a logical, testable process of science that is ground truthed with data obtained by direct observation, investigation and measurement in the field and in the laboratory. 3. Measure and calculate length, area, volume, mass and density of Earth materials using basic scientific equipment and techniques. 4. Develop and test physical and quantitative models of isostasy based on floating wood blocks and icebergs. Apply these concepts to basalt and granite densities to calculate the isostasy of average blocks of oceanic and continental crust. Introduction: Thinking About Time Two key features of geoscientists' temporal thinking distinguish them from the general population: They take a long view of time, and they expect low-frequency, high-impact events. Geoscientists have internalized the vastness of the age of the Earth and the relative brevity of human history. They can envision Earth in states drastically different from the planet they have personally experienced: an Earth without humans, an Earth without life, a hothouse Earth, a snowball Earth. In the long view of time, exceedingly slow processes such as erosion or evolution can effect huge changes, such as the removal of a mountain or the establishment of new species. Infrequent but powerful processes, such as floods, volcanic eruptions, landslides, and asteroid impacts, are routine rather than abnormal when considered across the whole of Earth's history. Most People Do Not Understand Geologic Time Substantial impediments stand in the way of society achieving a broad understanding of geologic time. Geologic time involves scales and events far removed from human experience; thus, envisioning the cumulative impact of slow processes or infrequent events over geological timescales is not intuitive. Scientists' timekeeping tools rely on exponential numbers, ratios, and proportional reasoning, all of which present well- documented difficulties for many students. Finally, some religious teachings oppose the idea of an old Earth. The most widely known geologic feature in the United States is probably the Grand Canyon. It is a mile deep and cuts through millions of rock layers that are like pages of an immense stone book of geologic history called the geologic record. The layers are like pages and vary in thickness, but no one layer is exactly like another. Each has distinguishing features such as tiny microscopic fossils or grains of sand and some have large fossil trees, dinosaur bones or ancient stream channels. These stone pages have recorded the events of the past and are there for us to read. 1

From:httphttp://images.nationalgeographic.com/wpf/media-live/photos/000/696/cache/skywalk-grand-canyon- arizona_69640_990x742.jpgl Spatial and Temporal Scales Spatial scales are used by geologists to study Earth materials from the smallest atoms to the entire globe. At each spatial scale of observation, they identify materials and characterize relationships. Each scale is related to the others as shown in the table below. SCALE OF OBSERVATION USED TO STUDY THINGS LIKE…. MEASURED IN…. GLOBAL ENTIRE PLANET AND ITS INTERACTIVE SPHERES THOUSANDS OF KILOMETERS OR MILES REGIONAL PORTIONS OF OCEANS, CONTINENTS, COUNTRIES, PROVINCES, STATES OR ISLANDS KILOMETERS AND MILES 2

LOCAL (OUTCROP OR FIELD SITE) SPECIFIC LOCATIONS THAT CAN BE PIN POINTED ON A MAP METERS AND FEET HAND SAMPLE (FIELD OR LAB SAMPLE SAMPLE OF A MINERAL OR ROCK, AIR, WATER OR AND ORGANISM THAT CAN BE HELD IN YOUR HAND CENTIMETERS, MILIMETERS AND INCHES MICROSCOPIC FEATURES OF A HAND SAMPLE THAT CAN ONLY BE SEEN WITH A HAND LENS (MAGNIFIER OR MICROSCOPE) FRACTIONS OF MILLIMETERS AND MICROMETERS ATOMIC ARRANGEMENTS OF THE ATOMS AND MOLECULES IN A SUBSTANCE Geologists also think about temporal scales of observation. They group the events, and relationships into paragraphs, chapters, sections and parts of geologic history that has occurred over epochs, periods eras and eons of time. The index of this geologic book is called the geologic time scale. Notice that it is a chart showing named intervals of the geologic record (rock units), the sequence in which they formed (oldest at the bottom) and their ages in millions of years. 3

From: http://factsanddetails.com/world.php?itemid=2213&catid=51&subcatid=323 Questions: 1. Match each item below with the appropriated scale that should be used to study it. a. The Grand Canyon ______________ b. The Mississippi River______________ c. The Earth’s Atmosphere______________ d. The Paul Spur Reef (this is located on highway 80 towards Bisbee, see picture at end of lab) _______________ e. The arrangement of atoms in a diamond________________ 4

f. A quartz crystal_____________ 2. Recall that the geologic record is the millions of rock layers that record events and times in geologic history. Also recall that the geologic time scale is a chart showing named intervals of the geologic record and their ages in millions of years. a. Compare and contrast the geologic record with a history book. How are they the same? How are they different? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ _______________In what geologic period of time did the first amphibian appear on Earth? _________________________________ b. What era was this? ________________________________ c. How many years ago was this? ________________________ d. How old is the Earth in millions of years? e. How long ago did man evolve? _________________________ f. When did the dinosaurs go extinct? ____________________ 3. During the Paleozoic, 290 to 350 million years ago two periods called the Mississippian and Pennsylvanian occurred. These two periods are lumped together and often referred to as the Carboniferous. Why do you think geologists call this time the Carboniferous? ______________________________________________________________________________ ______________________________________________ Field Geology and Lab Work The most reliable information about Earth is obtained by direct observation, investigation and measurement in the field and laboratory. Most geologists study outcrops – field sites where rocks crop out, stick out of the ground. The outcrops are comprised of minerals. Samples obtained in the field are often moved to the lab for further analysis. Physical and chemical analysis and tests can be done to determine the composition of the rock sample. Many times the rocks are crushed and powdered then put into a solution where a qualitative analysis is performed to determine the chemical composition. This technique is often used at mines to determine the percentage of gold, silver or other precious metals in an ore (host rock) and is called an assay. In an assay both a qualitative and a quantitative assessment are performed to determine how much and what type of elements are in the sample. The mineral chalcopyrite is a good example. Chalcopyrite is a copper bearing mineral that is mined, crushed, put into solution with detergents and water, and finally agitated. The chalcopyrite rises to the surface because it is less dense then the other constituents. These small grains are skimmed off and then smelted (roasted) to separate the copper from the other parts of the chalcopyrite and melted rock (slag). The remaining copper powder is then leached in sulfuric acid and subjected to electrolysis, whereupon the copper is 5

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help