Chapter 7 — Earth Science · Biology. These are 10 questions from the Magmo3 bank on this lesson, from easy to hard. Solve each one, then open "Show answer and explanation". Magmo3 has 52 questions on this lesson, each with an explanation.
Limestone, shale, marble, gypsum, sandstone and granite are given in the book as examples of
Correct answer: (A) Building materials
Explanation: One benefit of geology is searching for building materials such as limestone, shale, marble, gypsum, sandstone and granite (Book p.156).
The rock blocks found on both sides of the axial plane of a fold are called
Correct answer: (C) Fold limbs
Explanation: Fold limbs are the rock blocks found on both sides of the axial plane (Book p.161).
In a fault, the rock mass found above the fault plane is called the
Correct answer: (C) Hanging wall
Explanation: The hanging wall is the rock mass above the fault plane and the foot wall is the rock mass under it (Book p.162).
The imaginary line along which the axial plane of a fold intersects the surface of one of its layers is
Correct answer: (A) The fold axis
Explanation: The fold axis is the imaginary line of intersection of the axial plane with any surface of the layers; the axial plane itself is the imaginary plane dividing the fold into two equal parts (Book p.161).
Two geologists work for an oil company. The first uses physical sensitive devices to explore for oil traps; the second studies how oil forms, migrates and accumulates in reservoir rocks. Their branches are, respectively,
Correct answer: (C) Geophysics, then petroleum geology
Explanation: Geophysics explores oil traps, ore deposits and groundwater using physical sensitive devices, while petroleum geology deals with the formation of oil or gas, their migration and accumulation in reservoir rocks (Book p.156).
Which of the following is an importance of folds mentioned in the book?
Correct answer: (A) They determine the geological chronology of rocks
Explanation: Folds determine the geological chronology of rocks (older or younger). Hot springs arise along faults, joints helped in making obelisks, and an unconformity indicates absence of deposition (Book p.160, 163-164).
A thrust fault is a type of reverse fault. What distinguishes it from the ordinary reverse fault?
Correct answer: (A) Its fault plane is almost horizontal, with a low angle of dip
Explanation: The thrust fault differs from the reverse fault in that its fault plane is almost horizontal (low angle of dip), so its fractured rocks creep nearly horizontally; it is called a creeping fault (Book p.162).
In a vertical road cut, a steep fault plane dips towards the east (it slopes downward as it goes east). The same marker layer lies about 5 m higher in the eastern block than in the western block. What is this fault?
Correct answer: (B) Reverse fault from compression; the eastern block is the hanging wall that moved up
Explanation: The hanging wall is the rock mass above the fault plane; a plane dipping east passes beneath the eastern block, so that block is the hanging wall. It moved upward with respect to the footwall, which marks a reverse fault resulting from compression, and the steep plane rules out a thrust fault (Book p.162).
A section shows a lower group of sedimentary layers inclined towards the east, separated by an erosion surface from an upper group of sedimentary layers inclined towards the west. This surface is
Correct answer: (A) An angular unconformity
Explanation: An angular unconformity forms between two groups of sedimentary layers where the older group is inclined and the younger is horizontal, or where the two groups are inclined in two different directions (Book p.164).
In a section, an igneous intrusion cuts through a lower group of layers but stops at a surface and does not continue into the overlying layers. This indicates
Correct answer: (D) An unconformity surface between the two groups
Explanation: The presence of geological structures or igneous intrusions in one group of layers that do not exist in the overlying layers is one of the evidences of an unconformity (Book p.164).
The first 10 questions in every subject are free, each with an explanation.