Week 7

Week 7 Palaeontology and relative dating (1) Which of the following would NOT be considered a fossil? (a) a dinosaur bone (b) a dinosaur footprint (c) the impression of a fern leaf (d) a basalt dyke (2) In which of the following rocks would you be most likely to find fossils? (a) gneiss (b) limestone (c) granite (d) basalt (3) What type of fossil is shown in the picture? (a) body fossil (b) trace fossil (c) permineralized fossil (d) cast fossil (4) Why are feathers rarely found in the fossil record? (a) because birds usually die in dry environments (b) because feathers do not contain hard parts (c) because feathers are very small and thus are not well preserved (d) because birds die in forests, areas with high oxygen levels (7) What type of fossil forms when a buried organism decays or is dissolved, but the original shape is preserved in the sediment? (a) body fossil (b) trace fossil (c) mould fossil (d) cast fossil (8) Explain why the fossil record is incomplete. The fossil record is incomplete due to biases in fossilization, where not all organisms have equal chances due to factors like hard tissues and environmental conditions. Additionally, destructive forces, limited geological exposure, biological rarity, incomplete preservation, fossil loss, sampling bias, and the challenge of recognizing gradual evolutionary transitions contribute to this incompleteness. (9) What is a fossil? In what type(s) of rock are fossils most likely to be found? Why? A fossil is the preserved remains or traces of once-living organisms, and they are most likely to be found in sedimentary rocks. Sedimentary rocks, formed through the accumulation of sediments, provide conditions conducive to fossil preservation, including the protection of soft tissues, burial of organisms, and the layering that preserves fossilized structures.

(10) If the relative ages of two formations are known, what else about them can be inferred? (a) their absolute ages (b) their fossil assemblages (c) their lithologies (d) their relative position in the geologic column (11) Based on the figure below, what is the age of Layer 7 relative to Layer 3 (a) Layer 7 is younger than Layer 3 (b) Layer 7 is older than Layer 3 (c) Layer 7 and Layer 3 are the same rock type, so they are the same age (d) Their relative ages cannot be determined (12) Based on the figure above, which principle of stratigraphy could be used to determine the relative ages of Layer 7 and Layer 3? (a) the principle of fossil succession (b) the principle of original horizontality (c) the principle of lateral continuity (d) the principle of inclusions (13) Uniformitarianism is succinctly summarized by which phrase? (a) The future is the key to the present (b) The present is the key to the past (c) The past is the key to the present (d) The present is the key to the future (14) As understood by modern geologists, the principle of uniformitarianism implies that (a) the Earth has always had the same basic appearance that it has today (b) igneous, metamorphic, and sedimentary rocks are uniformly mixed throughout the crust (c) physical processes observed today (such as erosion and volcanic eruptions) have been active in the past at roughly the same rates (d) physical processes observed today (such as erosion and volcanic eruption) occurred much more rapidly in the past, quickly sculpting the Earth’s surface (15) In the area immediately surrounding an igneous intrusion, a host limestone is locally metamorphosed to produce marble. Which of the following statements is correct? (a) The intrusive igneous rock must be older than the limestone (b) The limestone must be older than the marble (c) The limestone must be younger than the marble (d) The relative ages of the three units cannot be determined with the information given (16) In an undisturbed sequence of sedimentary rocks, younger layers overlie older layers, according to the principle of (a) superposition (b) original continuity (c) original horizontality (d) uniformitarianism (17) If a basalt dyke cuts across a fault, what are the relative ages of the basalt and the fault? (a) The fault must be older, according to the principle of cross-cutting relationships Page 2 of 21

Principle of Superposition:  Description: In an undisturbed sequence of sedimentary rocks, the youngest rocks are at the top, and the oldest rocks are at the bottom. Principle of Original Horizontality:  Description: Sediments are deposited in horizontal or nearly horizontal layers. Principle of Unconformities:  Description: Gaps in the geologic record created by erosion or non-deposition, indicating periods of missing time. (21) The outcrop photograph below shows two different rocks. Indicate on the photo the oldest and the youngest rock. Which geological principal did you apply? The mafic rocks are younger as they didn’t have time to form crystals so they would have just formed around the original rock (23) The dark rock in the photo below is a sill that has intruded between older sedimentary rock layers. What is the evidence for this? Page 4 of 21

The evidence for the sill intrusion includes a parallel orientation to the sedimentary bedding, concordant contacts, distinctive mineralogy, smooth contacts, and potential columnar jointing. (32) Which of the following lists the divisions on the geologic column from largest (most general) to smallest (most specific)? (a) epoch, period, era, eon (b) period, epoch, eon, era (c) era, eon, epoch, period (d) eon, era, period, epoch (33) Use the Geological timescale below to answer the following questions: (a) during what era did the dinosaurs diversify and become dominant, Dinosaurs diversified and became dominant during the Mesozoic Era. (b) what is the age range of the era when Dinosaurs became dominant? The Mesozoic Era spans from approximately 252 to 66 million years ago. (c) when did the Late Proterozoic finish, in millions of years (Ma)? The Late Proterozoic finished around 541 million years ago. (d) when did the Late Proterozoic finish, in billions of years (Ga)? The Late Proterozoic finished around 0.541 billion years ago. (e) If the earth is 4.2 Ga in age, how many billions of years until the end of the Proterozoic? If the Earth is 4.2 billion years old, there were approximately 3.659 billion years until the end of the Proterozoic. (f) If the earth is 4.2 Ga in age, how many millions of years until the end of the Proterozoic? If the Earth is 4.2 billion years old, there were approximately 541 million years until the end of the Proterozoic (g) What is the name of the Period when the dinosaurs diversified? The period when dinosaurs diversified is the Triassic Period, which is the first period of the Mesozoic Era. (34) (a) When did the Dinosaurs disappear and what was the cause? Dinosaurs disappeared around 66 million years ago, and the cause is widely attributed to a combination of Page 5 of 21

 R: Relief or topography influences erosion and material transport.  P: Parent material, the rock or unconsolidated material, dictates the nature of weathering.  T: Time is a critical factor, representing the duration of weathering processes. (7) How is Bowen’s reaction series relevant in determining mineral stability at earth surface conditions? Bowen's Reaction Series is crucial for understanding mineral stability and rock formation. It helps predict the types of rocks that will form based on the cooling of magma. The series is valuable for identifying minerals susceptible to weathering at the Earth's surface and interpreting the evolution of igneous rocks (8) What are the similarities and differences between physical and chemical weathering? Make sure to address both what is the same and what is different. Similarities: Both physical and chemical weathering contribute to the breakdown of rocks, altering their characteristics and influencing soil formation. Differences: Physical weathering involves mechanical breakdown without changing the chemical composition, influenced by factors like temperature and pressure. Chemical weathering, on the other hand, transforms minerals through chemical reactions, influenced by water, atmospheric gases, and acids, leading to the formation of new substances (9) What is the resistance force? What happens when the resistance force exceeds the downslope force? What happens when the downslope force exceeds the resistance force? Resistance Force: Resistance force opposes downslope movement, involving factors like friction, cohesion, and obstacles. Outcome Scenarios:  Resistance > Downslope Force: Slope remains stable.  Downslope Force > Resistance: Slope becomes unstable, leading to mass wasting or slope failure. (10) Describe the geological history of Townsville from 300 Ma to today. Week 10 Geochronology (1) In an unweathered sample of igneous rock, the ratio of an unstable isotope to its stable daughter isotope is 1:15. If no daughters were present at the time the rock cooled below closure temperature, and the half-life of the isotope is 50 million years, how old is the rock? Page 7 of 21

(a) 200 million years (b) 400 million years (c) 750 million years (d) 1 billion years (2) Referring to the graph above, after one half-life has passed, what is the ratio of parent isotopes to daughter isotopes? (a) 16:0 (b) 8:8 (c) 4:12 (d) 2:16 (3) Two atoms of a single element that differ in number of neutrons are said to represent two distinct ________ of that element (a) isomers (b) isotopes (c) isotherms (d) atomic species (4) A radiometric age for a mineral crystal within an igneous rock measures the amount of time that has passed since the (a) atoms within the crystal were part of a body of molten magma (b) crystal solidified (c) temperature of the crystal became equal to surface temperatures (d) temperature of the crystal became equal to the closure temperature for the mineral (5) How is the half-life of a radioactive parent isotope defined? (a) the time it takes for half of the parent isotope to decay (b) half the time it takes for the parent isotope to completely decay (c) the time it takes the parent isotope to go through half the decay steps necessary to produce a stable daughter isotope (d) half of the average rate of decay of the parent isotope (6) How much of a radioactive parent isotope will remain after three half-lives have passed? (a) one-third Page 8 of 21

Use the graph to answer the question below: (d) Analysis of a rock sample shows that it contains 20% of parent isotope A and 80% of daughter B. If the half-life of parent A is 230 million years, what is the age of the sample? (11) Discuss what the numerical age represents when radiometrically dating a basalt, a gneiss, and a sandstone  Basalt: o Interpretation: Numerical age reflects the time since the basalt solidified, indicating when volcanic activity occurred.  Gneiss: o Interpretation: Numerical age signifies the time since metamorphism, revealing when the rock underwent heat and pressure.  Sandstone: o Interpretation: Numerical age represents the time since sediment deposition, offering insights into past landscapes and climates. Week 11 Deformation (1) An episode of mountain building is termed a(n) ________. (a) orogeny (b) phylogeny (c) aureole (d) slickenside (2) Which of the following is NOT an example of deformation? (a) faults Page 10 of 21

(b) folds (c) foliation (d) stratification (3) A body of rock affected by compressive stress will likely undergo ________. (a) shortening (b) stretching (c) shear strain (d) rotation (4) What four factors during viscous deformation would cause a rock to fracture instead of flow? Factors causing rocks to fracture during viscous deformation include high viscosity, low temperature, insufficient confining pressure, and rapid deformation rates. High viscosity and low temperature increase brittleness, while inadequate pressure and rapid deformation promote fractures instead of ductile flow (5) What is the difference between a fault and a fracture?  Fault: o Definition: A fault is a fracture in the Earth's crust along which there has been movement. It involves the displacement of rocks on either side. o Movement: Faults exhibit movement, categorized as either horizontal (strike-slip), vertical (dip-slip), or oblique. The rocks on either side of the fault have shifted relative to each other.  Fracture: o Definition: A fracture is a break or crack in a rock without significant movement on either side. It is a static feature and does not necessarily involve displacement. o Movement: Fractures do not necessarily involve movement or displacement of rock layers. They are breaks in the continuity of the rock mass. (6) If a fault plane is greater than 35° from horizontal and the hanging-wall block moves upward relative to the footwall block, the fault is called a ________ fault (a) detachment (b) normal (c) reverse (d) thrust (7) In the image below, the rocks have been bent into an elongate arch. This is a(n) ________. (a) anticline (b) basin Page 11 of 21

examples (use sketches if that helps).  Dip-Slip Fault:  Definition: Dip-slip faults involve movement primarily along the dip (inclination) of the fault plane. There are two main types: normal dip-slip and reverse dip-slip.  Normal Dip-Slip Fault: o Movement: The hanging wall moves down relative to the footwall. o Example: The Basin and Range Province in the western United States.  Reverse Dip-Slip Fault: o Movement: The hanging wall moves up relative to the footwall. o Example: The Rocky Mountains in North America. Strike-Slip Fault:  Definition: Strike-slip faults involve horizontal movement along the strike (direction) of the fault plane. There are two main types: right-lateral and left-lateral.  Right-Lateral Strike-Slip Fault: o Movement: The right side of the fault moves horizontally relative to the left side. o Example: The San Andreas Fault in California.  Left-Lateral Strike-Slip Fault: o Movement: The left side of the fault moves horizontally relative to the right side. o Example: The North Anatolian Fault in Turkey. Week 12 Mountains (1) What can be said about the rates of uplift and erosion in a mountain that is gaining elevation? In a mountain decreasing in elevation? What is the ultimate fate of all mountains on the Earth?  Mountain Gaining Elevation:  Uplift: The rate of uplift exceeds the rate of erosion. Geological forces, like tectonic uplift, are actively raising the mountain.  Erosion: While erosion is occurring, it is not keeping pace with uplift, resulting in a net gain in elevation.  Fate: The mountain will continue to rise, potentially reaching higher elevations over geological time. Mountain Decreasing in Elevation:  Uplift: The rate of uplift is slower than the rate of erosion. Geological forces may be subsiding or not keeping up with erosional processes.  Erosion: Erosion is actively wearing down the mountain, removing material at a faster rate than uplift is replacing it.  Fate: The mountain will gradually decrease in elevation and may eventually be eroded to a relatively flat surface. Ultimate Fate of All Mountains:  Over long geological time scales, all mountains will undergo processes of uplift and erosion.  The ultimate fate is often a feature known as a "peneplain" or a nearly flat, low-relief surface.  Through the processes of erosion, mountains are eventually reduced to landscapes of lower elevation. Why does continent collision cause an ocean to disappear? Page 13 of 21

 Subduction Zone Formation: o In the early stages of continent collision, one of the converging plates is usually an oceanic plate. o The denser oceanic plate starts subducting beneath the other plate, typically a continental plate.  Oceanic Plate Subduction: o As the oceanic plate subducts into the mantle, it undergoes partial melting, forming magma. o This magma rises through the mantle, creating volcanic arcs on the overriding plate.  Continued Convergence: o The convergence continues, and the subduction process leads to the consumption of the oceanic lithosphere.  Closure of the Ocean: o Over time, as the oceanic plate subducts and associated volcanic activity contributes to the growth of continental crust, the ocean basin narrows. o Sedimentation and tectonic processes contribute to filling the remaining oceanic basin.  Final Collision: o Eventually, the last remnants of the oceanic plate are consumed through subduction. o The two colliding continents come into direct contact, completing the collision.  Continental Suture: o The final stage involves the welding of the two continents, forming a continental suture. o The suture marks the closure of the ocean and the amalgamation of the two continental masses. Describe the tectonic processes that formed the Himalaya, beginning with the position of the Indian tectonic plate 120 million years ago. 1. Initial Position (About 120 Million Years Ago): o Approximately 120 million years ago, during the Late Cretaceous period, the Indian subcontinent was situated to the south of the equator and was part of the supercontinent Gondwana. 2. Indian Plate Separation: o Over the next tens of millions of years, the Indian plate separated from Gondwana and began its northward drift. 3. Oceanic Basin (Late Cretaceous to Early Eocene): o As the Indian plate moved northward, it created an oceanic basin, known as the Tethys Sea, between itself and the Eurasian plate. 4. Subduction and Collision (Eocene): o Around 50 million years ago (Eocene), the leading edge of the Indian plate began to subduct beneath the Eurasian plate. o Subduction led to the closure of the Tethys Sea, and the Indian plate continued its northward movement. 5. Continental Collision (Late Eocene to Early Miocene): o Approximately 40 to 50 million years ago, the Indian plate collided with the Eurasian plate. o The collision resulted in intense compression and uplift along the convergent boundary, initiating the formation of the Himalayan mountain range. 6. Himalayan Uplift (Miocene to Present): o The ongoing convergence between the Indian and Eurasian plates has led to the continued uplift of the Himalaya. o Intense tectonic activity, including thrust faulting and folding, has shaped the complex geological structures of the region. Page 14 of 21

(1) Which of the following is not a method employed to estimate paleoenvironmental conditions? (a) pollen counting (b) dendrochronology (tree ring studies) (c) sulphur emission monitoring (d) stratigraphic records (2) Which variables do Milankovic cycles take into account? (a) width, depth, and velocity (b) eccentricity, precession and obliquity (c) photosynthetic and cellular respiration rates (d) salinity, depth, and velocity (3) Current climate change trends show all of the following except? (a) sea level rise (b) increased CO 2 in the atmosphere (c) increased land ice (d) increased land temperatures (4) What is the current concentration of carbon dioxide in the atmosphere? (a) ~4 ppm (b) ~400 ppm (c) ~400 ppb (d) ~4000 ppm (5) How are greenhouse gases like carbon dioxide and methane different from other atmospheric gases like nitrogen and oxygen? (a) Greenhouse gases absorb thermal energy from the Sun and reradiate it, whereas other atmospheric gases reflect it (b) Greenhouse gases are more efficient at absorbing thermal energy and reradiating it than the other atmospheric gases (c) Greenhouse gases are found at higher levels of the atmosphere, where ozone is found. (d) Greenhouse gases are found at lower levels of the atmosphere, where ozone is found. (6) A runaway greenhouse effect is an example of ________.? (a) a positive feedback mechanism (b) a negative feedback mechanism (c) the hydrologic cycle (d) a steady-state condition (7) Which greenhouse gas has the greatest total importance in retaining radiant energy from the Earth? (a) CO 2 (carbon dioxide) (b) a negative feedback mechanism (c) the hydrologic cycle (d) a steady-state condition (8) How are carbon dioxide (CO 2 ) levels in the atmosphere affected by tectonic uplift of rocks and their resultant chemical weathering? Page 16 of 21

(a) CO 2 is removed from the atmosphere (b) CO 2 is added to the atmosphere (c) CO 2 is removed from the atmosphere by uplift, but returned by chemical weathering (d) They have no net effect on CO 2 (9) The figure below shows changes in sea level since the last ice age ended. Based on this, if the Earth were to enter another ice age similar to the last one, what would the sea level most likely do? (a) rise about 120 m (b) rise about 20 m (c) fall about 120 m (d) fall about 20 m (10) In the figure below, why is there a seasonal variation in carbon dioxide (CO 2 ) concentrations? (a) CO 2 concentrations rise and fall as photosynthesis decreases and increases (b) CO 2 concentrations rise and fall in conjunction with power plant emissions (c) CO 2 concentrations rise and fall with variations in solar radiation (d) The measurements were made in different places at different times of year (11) Provide an example of a positive feedback process as it relates to global climate change. A positive feedback process amplifies the effects of an initial change, leading to further changes in the same direction. In the context of global climate change, one example of a positive feedback loop involves the melting of polar ice and the associated decrease in surface reflectivity, known as the ice-albedo feedback. Here's how it works: Page 17 of 21

Earth's climate has experienced natural variations. Long-term changes result from factors like plate tectonics and variations in the sun's output, while short-term changes can be influenced by volcanic activity, solar cycles, and human activities Page 19 of 21

Week 13 Mineral Resources (1 ) Consult the figure below. Although granite contains iron atoms, we do not mine granite to produce iron because ________. (a) granite is too difficult to mine (b) iron concentration is too small to be economically mined (c) iron cannot be separated from the granite (d) iron is found only in isolated veins (2) In what types of rocks are ore minerals found in economic quantities? (a) only in igneous rocks (b) only in igneous and sedimentary rocks (c) only in igneous and metamorphic rocks (d) in sedimentary, igneous and metamorphic rocks (3) The stereotypical gold rush prospector panning for gold in a streambed is an example of exploiting ________ deposits? (a) magmatic (b) placer (c) residual mineral (d) sedimentary (4) Mineral-rich veins within plutons, deposited by hot groundwater into fractures within rock, characterize ________ deposits? (a) hydrothermal (b) placer (c) residual mineral (d) sedimentary (5 ) Which ore minerals are commonly found in ancient sedimentary deposits that are two billion years old? (a) copper sulphides (b) aluminum oxides (c) iron oxides (d) copper oxides Page 20 of 21