THE UNIVERSITY OF BRITISH COLUMBIA

Fall 2005 FINAL EXAMINATION

Dr. Maya Kopylova, Dr. Elizabeth Hearn

EOSC 110.102: Solid Earth

8:30 am December 13, 2005

FAMILY NAME: ______(please print)

GIVEN NAME: ______(please print)

STUDENT NUMBER: ______

CANDIDATES SIGNATURE: ______

SPECIAL INSTRUCTIONS:

This exam consists of 7 sides (including this page) and 40 Short answer questions

PLEASE MAKE SURE YOU HAVE A COMPLETE EXAM BEFORE STARTING.

LENGTH 2.5 hours. EXAM WORTH 70% OF COURSE

1. PLEASE HAVE PICTURE ID VISIBLE ON YOUR DESK

2. READ AND OBSERVE THE FOLLOWING:

No candidate shall be permitted to ask questions of the invigilator, except in cases of supposed errors or ambiguities in examination questions.

CAUTION: Candidates guilty of any of the following, or similar, dishonest practices shall be immediately dismissed from the examination and shall be liable to disciplinary action:

a) Making use of any notes or books

b) Speaking or communicating with other candidates.

c) Purposely exposing written papers to the view of other candidates.

3. SMOKING, CAKE BAKING OR ANY FORM OF MARTIAL ART IS NOT PERMITTED DURING THE EXAMINATION.

EACH QUESTION IS WORTH 1.75 MARKS.

1.  What is an artesian aquifer?

______( an aquifer in which the hydraulic head is above the ground surface -- so if you put in a well the water ‘erupts’ at the surface)

2.  Fill out the blanks in the next sentence with correct adjectives by choosing ‘negative’, ‘positive’, or ‘negligible’:

At the ground surface above a large empty cave in limestone, you should encounter a ______gravitational anomaly and a ______magnetic anomaly.

(negative, negligible)

3.  Fill in the blanks in the next sentence:

Canada’s largest recorded earthquake, a M8.1 event in 1949, occurred along the ______Fault, which is a ______fault.

(Queen Charlotte, strike-slip ( transform or right-lateral are ok too) )

4.  Why is the Dakota sandstone aquifer no longer artesian?

______( so much water has been removed that the hydraulic head is now below the ground surface)

  1. How are metamorphic rocks different from igneous and sedimentary rocks?

·  metamorphic rocks form from a preexisting rock whereas sedimentary and igneous rocks do not;

·  metamorphic rocks form from recrystallization in the solid state whereas sedimentary and igneous rocks do not;

  1. Draw a reverse fault and label the hanging wall and the footwall.
  1. What factors influence whether a rock will behave in brittle or ductile fashion?

The amount and rate of stress applied, the type of rock, and the T and P under which the rock is strained.______

  1. Why are metamorphic rocks containing between 10 and 20 wt. % Al in their compositions not mined as the Al ore?

Aluminium is impossible to extract from metamorphic rocks as in these rocks it resides in silicate minerals

  1. Why do inner planets consist mostly of rock and metal, but the Jovian planets mostly of gas?

There are 2 reasons for this:

·  Jovian planets are larger and therefore are able to attract and hold lighter gases;

·  Jovian planets are located further from the Sun where T are lower and gases are ices of the original nebula can be retained without vaporization

  1. What is the core composed of? How do we know this?

The core is made of Fe-Ni alloy with minor amount of Si, O and K. We infer this from studies of iron meteorites, which are natural samples of planetary material. Fe-Ni alloy is the most common natural material that satisfies the density requirements derived from geophysical observations on the total density of the Earth and the seismic velocities in the core.

  1. Why did not banded Fe ores form prior to 2.5 billion year ago?

The Earth prior to 2.5 By did not have oxygen-rich atmosphere and oceans necessary to deposit sedimentary Fe oxides in banded Fe ores.

  1. Draw a geologic cross-section featuring a nonconformity and explain how it developed.

A nonconformity resulted from sedimentation, deep burial, metamorphism and deformation of lower rocks, intrusion of plutons, uplift and erosion of several tens of kilometers of the upper crust and then renewed deposition of sedimentary rocks.

  1. What does the process of radioactive decay entail?

Radioactive decay is a spontaneous transformation of one element into another by emission of protons, neutrons and electrons.

  1. What do growth rings of a tree trunk and varved deposits have in common?

They both have darker and lighter layers that correspond to distinct seasons in the annual growth.

  1. What is the age of the oldest rocks on Earth? What is the age of the oldest rocks known? Why is there a difference?

The oldest rocks on Earth are ~ 4 By, whereas the oldest rocks known are meteorites (4.5 - 4.6 By). During the first ~ 0.5 billion years of Earth history, rocks in the crust remained too hot for the radiometric clock to start (>150 oC).

  1. Draw an oxbow lake and explain how it formed
  1. What is a rip current?

Rip currents are narrow currents that flow straight out to sea in the shore zone, returning water seaward that breaking waves have pushed ashore.

  1. Define an erosional and a depositional coast.

A coast significantly modified by wave erosion is called erosional. A coast with significant effects of wave and tide deposition are called depositional.

  1. How old is the Atlantic ocean?

The Atlantic ocean is ~150 million years old.

  1. Where (in oil, gas, coal, peat, oil shales or gas hydrates) does the most of Earth's carbon reside?

The most of Earth's carbon is stored in gas hydrates.

  1. What are stromatolites?

Stromatolites are fossilized build-ups of microbial mats that form on coral reefs and oceanic limestones.

  1. What rocks are commonly found in ophiolites?

Ophiolites are composed on deep-floor sediments, pillow basalts, sheeted dikes, gabbro and peridotites.