Lesson Worksheet: Geological Structures and Unconformities Geology

In this worksheet, we will practice identifying primary and secondary geological structures, describe unconformities, and compare between the different types of unconformities.

Q1:

Which geological structure represents a gap in the geologic record that is caused by erosion and nondeposition?

  • AA fault
  • BAn unconformity
  • CCross-bedding
  • DGraded bedding
  • EA fold

Q2:

Which of the following is a secondary geological structure?

  • ACross-bedding
  • BRipple marks
  • CGraded bedding
  • DMud cracks
  • EA fold

Q3:

True or False: Primary geological structures develop at the time of a rock’s formation, whereas secondary geological structures develop after a rock’s formation.

  • AFalse
  • BTrue

Q4:

True or False: A disconformity and a nonconformity are both types of unconformities.

  • ATrue
  • BFalse

Q5:

Which of the following is used as evidence to identify an unconformity in the field?

  • AThe presence of the same fossil type on both sides of the surface of unconformity
  • BThe presence of fine-grained sandstones directly above the surface of unconformity
  • CThe presence of rounded conglomerates directly above the surface of unconformity
  • DThe presence of younger rocks directly below the surface of unconformity
  • EThe presence of cross-bedded sandstones directly below the surface of unconformity

Q6:

Ripple marks are structures that form under the influence of climatic and environmental conditions. What are these types of structures called?

  • AUnconformity structures
  • BTectonic geological structures
  • CPrimary tectonic structures
  • DSecondary geological structures
  • EPrimary geological structures

Q7:

Which of the following statements describes the difference between a disconformity and a nonconformity?

  • AA disconformity exists between two parallel layers of sedimentary rocks, whereas a nonconformity exists between sedimentary rocks and igneous or metamorphic rocks.
  • BA nonconformity exists between two parallel layers of sedimentary rocks, whereas a disconformity exists between sedimentary rocks and igneous or metamorphic rocks.
  • CA disconformity exists between two parallel layers of sedimentary rocks, whereas a nonconformity exists between layers of rocks that have opposing angles of dip.
  • DA nonconformity exists between sedimentary rocks and igneous or metamorphic rocks, whereas a disconformity exists between layers of rocks that have opposing angles of dip.

Q8:

Which of the following statements defines an unconformity?

  • AAn unconformity is a surface of nondeposition or erosion that represents a gap in the geological record.
  • BAn unconformity is a force that causes relative displacement of rocks.
  • CAn unconformity is a sequence of rocks that does not contain any fossils.
  • DAn unconformity is the horizontal compression of rock layers that causes a bend in the rock strata.
  • EAn unconformity is a sequence of rocks that does not contain any gaps in the geological record.

Q9:

Which of the following statements about erosional surfaces is correct?

  • AA nonconformity is an erosion surface that separates two nonparallel sedimentary layers.
  • BA fold is an erosional surface that separates two nonparallel sedimentary layers.
  • CA disconformity is an erosional surface that separates two nonparallel sedimentary layers.
  • DA fault is an erosional surface that separates two nonparallel sedimentary layers.
  • EAn angular unconformity is an erosional surface that separates two nonparallel sedimentary layers.

Q10:

True or False: An unconformity is a type of primary geological structure.

  • ATrue
  • BFalse

This lesson includes 7 additional questions for subscribers.

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