quiz 4

Question 1

what feature indicates the top of a sedimentary bed, or bed surface, marker?

Answer 1

mud cracks, graded bedding, fossil footprints and scour marks

Question 2

true or false, obvious sandstone beach deposits overlain by marine mudstone indicate transgression of the sea

Answer 2

true

Question 3

what are the methods to determine numerical age

Answer 3

-carbon-14 dating
-radioactive decay of uranium to lead
-fission-track dating
-dendrochronology (tree ring dating)

Question 4

true or false, the oldest rocks found so far in our solar system are 4.57 billion-years-old meteorites, leading scientists to conclude that this is the approximate age of the Earth

Answer 4

True

Question 5

a mud of fine calcite and/or aragonite shell debris could become which rock?

Answer 5

micrite

Question 6

what are the names that fit the three descriptions: Age of Mammals, Age of dinosaurs and longest-named geologic unit of time

Answer 6

Cenozoic, Mesozoic, Precambrian

Question 7

what is the most logical past environment to have produced a deposit consisting of layers of unsorted, unstratified sedimentary coasts, clay-sized to boulder-sized?

Answer 7

glacial valley

Question 8

before the development of isotopic dating methods, the age of the earth was estimated by?

Answer 8

-counting the age of people within succesive generations as described in the bible
-comparing rates of change on Earth’s surface today with the geologic record
-calculating the rate of cooling of Earth from an assumed initial temperature
-estimating evolution rates from the fossil record

Question 9

sedimentary rocks can form…

Answer 9

-by the precipitation of minerals from water solution
-by the cementing together of loose grains of preexisting rock
-from shell fragments or carbon-rich relicts of plants

Question 10

what is the most logical environement to have produced a deposit consisting of layers of well sorted sandstone with cross beddings several meters high

Answer 10

sand dunes

Question 11

true or false, lithification is a general term used to describe all the physical, chemical and biological processes that make a sedimentary rock from sediments

Answer 11

true

Question 12

as sediment is transported downstream, away from its point of origin, the particles found in the stream become…

Answer 12

-of greater resistance
-rounder
-smaller
-better sorted by size

Question 13

uniformitarianism…

Answer 13

is illustrated by scientists’ seeing pillow lava form only underwater, then theorizing that pillow lava found high in the mountains today did nevertheless form underwater

Question 14

go see pictures q.14

Answer 14

1,3,2,4

Question 15

what assumption you might use in radiometric age-dating would cause you to underestimate the age of a rock?

Answer 15

the rock had been a closed system since the time it formed, but it had been metamorphosed enough that some daughter product, no parent product, escaped

Question 16

when sea level rises, the shoreline migrate inland, flooding the land and depositing coastal sediments over preexisting terrestrial sediments. this process is called?

Answer 16

transgression

Question 17

what is the proper listing of detritus terms, grading from smallest to largest

Answer 17

mud, silt, sand

Question 18

rocks formed dominantly from the calcium carbonate shells of marine organisms are classified as … and called ….

Answer 18

biochemical and limestone

Question 19

flint and jasper were prized in early human cultures because…

Answer 19

they broke with conchoidal fracture and thus made good cutting tools

Question 20

closure temperature is ?

Answer 20

the temperature at which a rock system ceases to interchange parent or daughter product with surrounding material

Question 21

what geological feature was not formed by sedimentary processes but rather by igneous processes

Answer 21

Columbia River Plateau (LIP), Washington

Question 22

an organic sedimentary rock originated as decaying plant matter is?

Answer 22

coal

Question 23

ripple marks on a bedding plane…

Answer 23

could suggest an ancient stream bed or a seashore

Question 24

a non marine clastic sedimentary rock composed of angular fragments surrounded by matrix is…

Answer 24

breccia

Question 25

true or false, radiometric dating can be used only if theres some uranium present in the rock

Answer 25

false

Question 26

a clastic sedimentary rock with clay and silt-sized grains that breaks in thin sheets is called

Answer 26

shale

Question 27

geologists find a thick sequence of alternating shales and sandstones. the probable depositional environment and interpretation of these are?

Answer 27

deep marine deposits near the continental shelf

Question 28

indentify the true statement:
-chemical sedimentary rocks are crystalline in texture
-Flint, jasper, agate, and petrified wood are all varieties of the siliceous rock chert
-both chert and limestone may have either chemical or biochemical origin
-gypsum and halite are evaporite minerals
-all of the above are correct

Answer 28

all the answers are correct

Question 29

ripple marks, dunes, and cross bedding are useful indicators of ?

Answer 29

current direction

Question 30

True or false, the presence of mudcracks indicates the sediments lithified in deep water

Answer 30

False