Geology Test 4

Most Dry lands (low latitude deserts) are located in the vicinity of ____degrees north and south latitude of the equator. 30 Seamounts are volcanoes that form on the ocean floor. The East coast of North America considered a _____ Continental Margin? Passive The San Andreas Fault in California is the boundary between the North American and Pacific plates is a transform fault, however, when we think of the sense (direction) of the movement it is called a ______. Strike-Slip fault Submarine canyons found on the continental slope and rise are believed to have been created____. by turbidity currents. Which of the following is not true about deep ocean trenches: They are long and narrow depressionsThey are sites where plates plunge back into the mantle They are geologically very stable. They are geologically very stable _____continental margins typically exhibit wide, extensive, continental shelves. Passive The _____lies at the base of the continental slope. Continental rise Geologically, what is the best way to explain accumulations coral limestone beneath most atolls? The volcano never reached, but came close to the sea level surface, allowing for the coral to accumulate. The term ____refers specifically to geologic mountain building. Orogenesis An erosion removed the tops of mountain ranges, the crust will buoy (float) upward (like an iceberg would) causing fault movement. This is an example of____. Isostacy Determine the type of geological structure. Normal fault Determine the type of geological structure. Reverse fault An unconformity is a buried _____. Surface of erosion separating younger strata above from older strata below. A linear down folded structure with the youngest strata in the center is termed____. Synclines Large circular down warped structures, like those found in Michigan and Illinois, are referred to as _____. Basins A "Andean" type plate boundary is a classic demonstration of how the mountain building process works at an ocean to continent plate boundary. At a subduction zone Guyots are_____ Underwater flat-topped seamounts Which of the following best characterizes an angular unconformity Tilted strata lie below the unconformity, and bedding in younger strata above is parallel to the unconformity. In mountain regions, the Earth's crust is_____ thicker than average Which of the following geologic observations would not bear directly on working out the sequence of geologic events in an area? inclusions of sandstone in a granite plutona dike of basalt running through a sandstone The mineral content of granitean unconformity between granite and sandstone. The mineral content of granite What fundamental concept states that in a horizontal sequence of conformable sedimentary strata, each higher bed is younger than the bed below it? Law of superposition What of the following refers to the investigative process by which geologists identify and math sedimentary strata and other rocks of the same ages in different geographic areas? Correlation Does unconformity come before intrusion? Yes Which one of the following represents the greatest expanse of time in the Geologic Time Scale Precambrian The half-life of a radioactive element is 6000 years. A sample of rock is 12,000 years old. How much of the original radioactive element (parent product) would remain today? one-fourth Define nonconformity an unconformity that separates crystalline rocks,either igneous or metamorphic, from sedimentary rocks. The mountains on the Western North American Continent (Alaska in particular) were produced in part by the addition of small crustal block to the margin of the continent. THese crustal fragments having distinct geologic histories are known as____. Terranes What is the age of the Earth accepted by most scientists today? 4.5 billion years What is an essential characteristic of an index fossil? The organism only lived for a short period of geologic time. What combination favors folding rather than faulting? High temperature and high confining pressure ____is the process (question 28) that occurs at active continental margins where sediments and older rocks are scraped off a descending plate and piled against the edge of the overriding plate. Accretion. Four factors that influence the strength of rock and how it will deform temperature, confining pressure, rock type, and time. What is the one best measure of the wetness or dryness of a desert region? Difference between annual precipitation and evaporation potential. Look at the map view. -l Desert pavement is the result of ______ Deflation from wind. _____are not associated with a mid ocean ridge deep ocean trenches. How does wind transport sand grains? by saltation as part of the suspended load. T/F the predominant particle size in loess deposits is gravel and boulders. F T/F a playa is a dry, flat lake bed on the floor of a desert basin. T Desert definition____ Despite infrequent rainfalls, erosional and depositional features of running water are important in desert landscapes. A worm would stand a poor chance of being fossilized because_____ worms have no hard parts The ____ is the idea or concept that ancient life forms succeeded each other in definite, evolutionary, pattern and that the contained assemblage of fossils can determine geologic ages of strata Principle of fossil succession An echo sounder operates by measuring the time required for a______ sound pulse travels from a ship to the seafloor and back. Look at map view. Anticline Long sand dunes that are oriented more or less parallel to the prevailing wind with limited supplies of sand are called ______ dunes. Longitudinal Solitary dunes who tips point downwind are_____dunes. Barchan T/F abyssal plains owe their relatively featureless topography to thick accumulations of sediments that have buried an otherwise rugged ocean floor. T There is a considerable span of time for which there is no deposition and/or erosion between two of the sedimentary layers. What was discovered? Disconformity Sandstone strata and a mass of granite are observed to be in contact. What statement can be made? The granite is older if the sandstone contains inclusions of the granite. Deposits that form as a result of dense-sediment-laden water running down submarine canyons are called_____ Turbidites ____bedding occurs in the sedimentary deposits formed in question 51. This type of bedding shows fine grained sediments at the top and coarser sediment on the bottom of the layer. Graded Streams in desert regions that flow intermittently are referred to as______. Ephemeral Deserts have discontinuous drainage pattern of intermittent streams that do not eventually flow to the ocean. THey are said to have ____drainage. Interior T/F trenches form the deepest parts of the ocean basins. T T/F Steppes are the driest of the true desert lands F Interestingly shaped stones produced by wind abrasion are called_____ Ventifacts Dip faults have mainly ____ movement vertical Left lateral____ road moves left T/F fractures in rock that have not involved any fault slippage are called joints T