ROCKS OF THE LAKE CAYUGA BASIN, NEW YORK

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1 Bedrock Correlation Name: Introduction: The Finger Lakes Region of New York State is underlain by rocks of Devonian Age. Use your reference tables to determine the types of rocks that outcrop around the Finger Lakes: The rocks include Patterns of deposition and the existence of various fossils indicate that these rocks were deposited in a shallow sea that covered much of the central United States during that time. Over 1200 meters of sedimentary rocks are deposited in the Devonian of upstate New York (that s about ¾ of a mile). We can see continuous outcrops of over 100 meters of thickness in quarries (where stone is mined for building materials), in road cuts, and where rivers have cut deep gorges into the rocks. No one, however, has found a place where the entire 1200 meters exists in a single outcrop. How do you suppose geoscientists form a complete view of these rocks? Imagine for a moment that you have several Earth Science books without page numbers and each with large sections of pages missing. If, among the many pieces you had, there were some overlapping pages, you might be able to reconstruct a complete book from the pieces. Geoscientists do this with rock outcrops. They try to find similar rocks that overlap in different outcrops in an attempt to match them up, or correlate them. In this lab, you will correlate nine different outcrops from the area around Lake Cayuga to develop a complete 14 inch thick model of the rock layers, or stratigraphic column, of the Devonian in that area. Each inch of your model represents about 10 meters of outcrop. The table below describes the actual rock units that outcrop in that area. FORMATION Sherburne Shale Geneseo Shale Tully Limestone Moscow Shale Ludlowville Shale Skaneateles Shale Marcellus Shale Onondaga Limestone Oriskany Sandstone Manlius Limestone Rondout Dolostone ROCKS OF THE LAKE CAYUGA BASIN, NEW YORK DESCRIPTION Shale at bottom with increasing sand toward top Black Shale about 10 meters thick Limestone about 3 meters thick Shale with limestone base about 15 meters thick Shale, about 25 meters thick Shale with limestone cap, about 28 meters thick Mostly shale, black at base, then thin limestone, 4 meters of limestone at top. About 25 meters thick Highly fossiliferous limestone over 25 meters thick Thin sandstone about 1.2 meters thick Finely layered limestone about 7.6 meters thick Dolostone about 7.5 meters thick

2 Procedure: You ve learned that superposition is an important concept when interpreting the rock record. It s important to know which way is up! Each of the outcrops are marked with the letter T at the top of the outcrop. 1. Carefully cut out the 9 outcrops. 2. Lay the outcrops out on your desk and correlate them. You will find that fossils are sometimes useful and sometimes misleading. The rock descriptions in the table on the previous page will be helpful. The final product should have a stair-step pattern. 3. When you have all the layers matched up, use a glue stick to attach them to a large sheet of paper. 4. Use the thicknesses and descriptions on the table on the first page to mark the top and bottom contacts of each formation. Draw straight lines across your paper, extending beyond the cutouts to show the locations of the rock formations. A rock formation may include more than one type of rock. Do not draw lines separating each layer of rock. Label each formation. Neatness counts. Answer the questions below neatly and completely. 1. Which three formations are made up of entirely limestone? 2. Which formations are made up of entirely shale? 3. The Tully limestone stands out as a ridge of rock between valleys. What happened to the missing rock? Why was the Tully limestone left behind? 4. Which is deposited closest to the shore of a sediment collecting basin: sandstone, siltstone, or clay? Why?

3 5. Which formation was most likely once a beach? How do you know? 6. Look at the description of the Sherburne. Was there a transgression or a regression when it was being deposited? How do you know? 7. The Onondaga contains a few thin layers of volcanic ash (not shown). Why is volcanic ash useful for correlating layers of sedimentary rock? 8. The Onondaga also contains fossils of crinoids, coral, trilobites, and brachiopods. Why are there no fossil birds or grasses? 9. What characteristics make an organism a good index fossil? 10. What do historical geologists use index fossils for? 11. Why are the Eurypterids in these cross sections not useful as index fossils? 12. Do you think that humans will be a good index fossil one day? Explain.

4 The Marcellus Shale and Hydraulic Fracturing What Is Shale Gas and Why Is It Important? Shale gas refers to natural gas that is trapped within shale formations. Shales are fine-grained sedimentary rocks that can be rich resources of petroleum and natural gas. Sedimentary rocks are rocks formed by the accumulation of sediments at the Earth's surface and within bodies of water. Common sedimentary rocks include sandstone, limestone, and shale. Over the past decade, the combination of horizontal drilling and hydraulic fracturing has allowed access to large volumes of shale gas that were previously uneconomical to produce. The production of natural gas from shale formations has rejuvenated the natural gas industry in the United States. Where does natural gas come from? Origin - The natural gas we use today began as microscopic plants and animals living in the ocean tens of millions of years ago. As they thrived, they absorbed energy from the sun, which was stored as carbon molecules in their bodies. When they died, they sank to the bottom of the sea and were covered by layer after layer of sediment. As the plants and animals became buried deeper in the earth, heat and pressure began to rise. The pressure and heat transformed the biomatter and produced natural gas. Migration - After natural gas was formed, it tended to migrate upward through tiny pores and cracks in the surrounding rock. Some natural gas seeped to the surface, while other deposits traveled until they were trapped under impermeable layers of rock, such as shale or clay. These trapped deposits are where we find natural gas today. Extraction - Removal of natural gas can be accomplished through either vertical or horizontal drilling. Chesapeake uses both methods, but specializes in horizontal drilling and hydraulic fracturing to extract natural gas from shale or deep rock formations. The horizontal drilling method uses vertical drilling from the surface down to a desired level. Then, the drillbit turns at a near 90 degree angle and bores into a natural gas reservoir horizontally. Hydraulic fracturing is a tried and tested technique, being used more than 1 million times in the past 60 years, that involves pumping fluids or water into the wellbore with enough pressure to create small microfractures, or fissures, in the rock formation to enhance recovery. It is this fracture through which natural gas moves into the wellbore and then up to the surface.

5 What Are the Marcellus and Utica Plays? The term play is used in the oil and gas industry to refer to a geographic area which has been targeted for exploration. An area comes into play when it is generally recognized that there is an economic quantity of oil or gas to be found. Both the Marcellus and Utica Shale plays are geological formations that were formed by the accumulation of sediment into a sea. This formation was eventually buried over many thousands of years and compressed to produce an organic-rich black shale. Why Now? Although throughout the geological world, Marcellus and Utica Shale plays have been identified as potentially rich in fossil fuels, it was not until recently that the industry has invested into exploration. Two factors are clearly present in the ramp up in exploration and production (E&P) activities related to these plays. First, the success of the Barnett Shale play in North Central Texas has allowed companies to transfer the hydraulic fracturing technology to other areas, such as the Fayetteville Shale play (Arkansas), Haynesville Shale play (Louisiana and Eastern Texas), and the Marcellus and Utica Shale plays. Second, the population centers of Northeastern U.S. are very close in proximity to the both the Marcellus and Utica Shale plays, which results in lowering the cost of bringing natural gas to the Northeast market. What Does the Future Hold? As America demands more and more energy, the role that natural gas will play in that demand is uncertain. One thing that is certain is the Marcellus and Utica plays are shaping up to be key suppliers for domestic natural gas. Impacts from this industry are uncertain as well. Historically, the energy industry has gone through times of "boom and bust" and is driven by the economic conditions present across the nation. The industry is also known for paying a higher wage, on

6 average, compared to an equivalent manufacturing job. One thing that is not uncertain is that the natural gas industry associated with shale gas exploration will give the nation another source to potentially reduce the intake of foreign supplies of natural gas. The Lifespan of Shale Gas Dividing the natural gas development process into three phases (pre-drilling, drilling, and production), industry surveys used to create the 2011 Pennsylvania Statewide Marcellus Shale Workforce Needs Assessment show that 98% of natural gas exploration and development jobs are found in the pre-drilling and drilling phases of bringing a well into production. No one can accurately estimate how long the drilling phase will last within the Marcellus and Utica plays, but estimates range from 10 to 70 years which in part reflect uncertainty created by future fluctuations in commodity prices, economic conditions, and technological changes among other variables. A number of drilling scenarios are possible for future shale gas development, and they include a relatively quick flurry of activity that subsides when drilling moves to another location, high-intensity drilling that jumps from hotspot to hotspot and moderate and sustained drilling across the Appalachian Basin lasting for decades. Each development scenario changes the direct workforce requirements and opportunities for business development and entrepreneurship Questions Define the following words. Accumulation - Uneconomical - Rejuvenated - Thrived - Migrate - Impermeable -

7 Bore - (this has more than one meaning, choose carefully) Proximity - Domestic - 1. What do humans use natural gas for? 2. What is the slang term for hydraulic fracturing? (Hint: It s not in the reading) 3. Why is natural gas found underneath impermeable layers of rock? 4. Could there be natural gas in the layers of rock underneath your home? How do you know? 5. Explain horizontal drilling.

8 6. Horizontal drilling can be used to take natural gas from underneath neighboring properties. Ownership of property doesn t extend down underground to the center of the Earth. People don t technically own the natural gas beneath their homes. They simply own the surface. How do you feel about this? Would you be angry if someone took natural gas from underneath your property? What kind of problems could this cause for you? 7. Why might people in this area want the natural gas trapped under the Marcellus shale to be extracted? 8. If we begin drilling for our own natural gas, will we need to buy any from other countries anymore? Why or why not? 9. Why will the jobs that hydraulic fracturing creates in an area go away over time?

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