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Northern Arizona University *

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184L

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Geology

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Jan 9, 2024

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Name: Sam Glaberman Lab Instructor: Helen Eifert Lab Section: 1237 AST-184L Lab 2 - Rock Identification Objectives The objective for this lab is to learn basic rock identification. We will use these skills to understand astrobiological implications of the rocks we find on other planets. Materials Pencil/pen, hand lens, grain size scale, hydrochloric acid Introduction Let’s assume there is currently no life on Mars but there was in the distant past, maybe 2 billion years ago. Since we cannot time travel, we’re unable to directly observe that early Martian life, but, luckily for us, there are plenty of rocks on Mars that are at least that old. Rocks tell us a story about the environment that they form in. How does the geologic record help our search for life in the universe? The geologic record can tell us about ancient sea levels and weather (sedimentary rocks), volcanic activity (igneous rocks), mountain building (metamorphic rocks), and even preserve ancient life directly in the form of fossils (also sedimentary rocks). In this lab you will learn how to differentiate the major rock types, identify several rocks, and relate that information to the search for life in the universe.

Name: Sam Glaberman Lab Instructor: Helen Eifert Lab Section: 1237 Exercises Let’s start with the basics, what can your basic senses tell you about the rocks in front of you? Hold the rocks in your hands, look at them, feel them, smell them, and record what your senses tell you. Exercise 1 - Basic senses Rock label Sight Smell Touch A It looks like rigid light brown rock Dusty Feels chalky B It looks a lot more smooth Smells like clay Rigid but soft C It has clups of different browns and black Smells like dirt flakey D This one looks a bit fancier. It looks like there are little cyrstals/gems in it Smells dirty and dusty Bumpy and smooth in crevases E It looks like a clump of himilayan salt Smells perfumy bumpy F This one reminds me of marble. sharp Smooth with small bumps G This one looks a little shiney Smells dirty lumpy H This looks like a planet Chocolate Holey I This one looks white with spots Cement A little bumpy but flat too J This looks flat Smells like dirty Soft K This one has lots of lines Golf store Rigid but smooth Once you’re finished with this section, ask your instructor for (1) a hand lens, (2) a grain size chart, and (3) a vial of hydrochloric acid.

Name: Sam Glaberman Lab Instructor: Helen Eifert Lab Section: 1237 Exercise 2 - Analysis and measurement Use the materials provided (grain size chart, hydrochloric acid, and hand lens) with the below reference charts to answer the questions below.

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Name: Sam Glaberman Lab Instructor: Helen Eifert Lab Section: 1237

Name: Sam Glaberman Lab Instructor: Helen Eifert Lab Section: 1237 Sedimentary rocks Which sample(s) reacts with hydrochloric acid (HCl)? A B C D E F G H I Which sample(s) have sand sized grains? A B C D E F G H I Which sample(s) have silt sized grains? A B C D E F G H I Which sample(s) contain fragments of other rocks? A B C D E F G H I Igneous rocks Which sample(s) have interlocking crystals? A B C D E F G H I Which sample(s) have potassium feldspar, quartz, and mica/amphibole? A B C D E F G H I Which sample(s) have large crystals and are mostly plagioclase feldspar? A B C D E F G H I Which sample(s) are dark with large, coarse crystals? A B C D E F G H I Which sample(s) have numerous vesicles? A B C D E F G H I Which sample(s) are light in color and low density? A B C D E F G H I Interpretation Which rock(s) are biogenic? A B C D E F G H I Which rock(s) are potentially evidence of water? A B C D E F G H I Which rock(s) are evidence of volcanic activity? A B C D E F G H I Which rock(s) are evidence of mafic volcanism? A B C D E F G H I Which rock(s) have ~20% light/dark minerals? A B C D E F G H I Which rock(s) are evidence of felsic volcanism? A B C D E F G H I Which rock(s) have ~1% light/dark minerals? A B C D E F G H I Which rock(s) are evidence of intrusive volcanism? A B C D E F G H I Which rock(s) are evidence of extrusive volcanism? A B C D E F G H I

Name: Sam Glaberman Lab Instructor: Helen Eifert Lab Section: 1237 Exercise 3 - Final notes and classification Color (light/d ark) Grain size (mm) Large crystal s? (Y/N) Rock type* (S/I) Rock name A Light 0.063 mm n Sedimentary Limestone B Dark 2 mm n sedimentary C Light n Sedimentary D Light y Sedimentary conglomerate E light F dark 0.063 mm no igneous G dark 0.063 mm no igneous H dark igneous I light J dark K dark 1 mm no metamorphic Gneiss *S = sedimentary, I = Igneous

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Name: Sam Glaberman Lab Instructor: Helen Eifert Lab Section: 1237 Report Questions 1. If alien and terrestrial (Earth) fossils were found in the Grand Canyon, what differences between them would you imagine finding using your sight/smell/touch tests? If we found alien and Earth fossils in the Grand Canyon, we might see differences using our senses. Alien fossils might look strange, smell different if any organic material remains, and feel unusual in terms of texture. 2. If the Perseverance rover finds microbes in the mud of Jezero Crater (Mars), what is the reaction of humanity? (Scan the QR code if you want to know more about Jezero) If the Perseverance rover found microbes in the mud of Jezero Crater (Mars), I think people would feel all sorts of different emotions, maybe excited, curious, nervous. Scientists and space agencies would probably study it more, and people everywhere would be talking about what it means for life beyond Earth. There'd also be discussions about how to keep things clean. 3. Close your eyes, imagine where life first developed on Earth. Now, fast forward several

Name: Sam Glaberman Lab Instructor: Helen Eifert Lab Section: 1237 billion years and imagine you found that environment preserved in the rock record, what does the rock look like? If we came accross the environment where life initially developed on Earth preserved in the rock record after billions of years, we might encounter ancient sedimentary layers. These rocks could display fine layering, suggesting the calm deposition of sediments in watery environments. Within these layers, we might find mineralized traces of ancient microbial mats or stromatolites, along with chemical clues pointing to the emergence of life in that ancient setting

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