GEOL 100: Video Worksheets 1

in progress; 5 and 6 (Ring of Fire) are their own flashcards (on study guide they're combined)

What vital discovery did geologists make about meteorites that have been found on Earth?

Meteorites are older than any rocks found today on Earth

What was the name of the fundamental mechanism that held the little clumps of slat together in the International Space Station experiment in 2003?

static electric charges

What caused the earth to heat up and completely melt soon after it formed?

The incorporation of radioactive elements—which give off heat—from space into earth

Why do scientists use meteorites to determine the age of the Earth?

Meteorites are made up of similar materials as Earth’s rocks, and they were created around the same time as the Earth.

According to the “modern radiometric dating techniques” the Earth is…

4.567 or ~4.6 billion years old.

Why didn’t the scientific community accept Wegener’s idea?

They didn’t accept Wegener’s proposed explanation for the mechanism behind continental drift. 

Why did American scientists react more negatively to Wegener’s ideas than European scientists?

1. Wegener’s theory went against American principles of buoyancy (isostacy)

2. American scientific method differed from the German one

   1. Americans = base on empirical data (exploration, observation)

   2. Germans = base on more modern sci. method; read up on topic, learn a bit about it, create a hypothesis, observe and collect data related to hyp etc

What radical new idea was proposed in 1960 that explained the new features found on the ocean floor?

Seafloor spreading hypothesis

Seafloor spreading was finally accepted by the discovery and existence of…

magnetic anomalies on the seafloor 

Most direct evidence for plate tetonic movement today comes from what?

GPS

What did the crew of the 1872 HMS Challenger expedition discover about the depth of the western Pacific Ocean 200 miles off the Island of Guam?

4,475 fathoms; 5 miles below the surface there was some kind of hole??

How does SONAR chart (i.e., map) the seafloor?

It sends down sound waves, and the time it takes for the sound to travel back is measured 

• “ using the time difference between creating a sound and receiving its echo” (NOAA)

What did detailed SONAR maps (completed in 1951) reveal about the deep hole found by the original HMS Challenger expedition?

The deep hole isn’t a hole but part of a trench; 1,500 miles long, 7 miles deep

• it runs twice the length of california

  • 1500 miles from southeast of Guam to northwest of Mariana islands

• 30x deeper than the Empire State building

What is the major problem (for scientists and engineers) at the bottom of the trench?

Pressure 

• equal to 50 jumbo jets squeezing you; 16,000 psi

Why is the Pacific Plate the fastest moving of the 9 major plates on planet Earth?

It’s the fastest moving as it is surrounded by dozens of destructive trenches like the marianas

What type of volcano is found all around the Ring of Fire?

Stratovolcanoes (or composite volcanoes)

Why are Ring of Fire volcanoes so dangerous and deadly?

Blocky lava = high viscosity

What food is a good analogy for Hawaiian-like lavas? Why

Honey as both the lava and the honey are runny

What food is a good analogy for Alaskan (and other Ring of Fire) lavas? Why

Peanut butter as the lava and the peanut butter are both viscous

What is more dangerous than the initial explosion of a volcano?

The superheated avalanche of ash and gas shoots up in the air and comes back down rolling off the sides of the volcano

• 1300 degrees

• 100 miles/hr

Volcanic ash + gases = pyroclastic material

What does the mineral Hornblend tell us about the formation of the sticky lava?

It tells us there’s water underground. Hornblende only forms where there’s water. This means water is key in the formation of sticky lava.

What was the biggest misconception about earthquakes in Southern California?

That California already had the big earthquake

Why will an earthquake along the Puente Hills fault be “the earthquake from hell” for the Los Angeles Basin?

The basin will shake like jello as it is made up of sand and gravel

What determines the amount of damage after an earthquake?

The distance from the fault

Why was the March 10th 1933 Long Beach earthquake one of the most important in the history of the world?

resulted in the world’s first building code

Why is non-ductile reinforced concrete bad?

Non-ductile is brittle, it doesn’t bend

Where did the 1906 San Francisco Earthquake Originate?

2 miles off of the golden state bridge

What process was occurring along the coast of California prior to the existence of the San Andreas fault?

Subduction

How long ago did the San Andreas Fault form (ie. when was it born)

20 million years ago

What can geologists predict about earthquakes? (3)

1. The probability of an earthquake occurring on a given fault

2. which fault is likely to have an earthquake

3. How big the earthquake might be on a given fault 

What did geologists discover about deep fault movement along the San Andreas Fault? Is it good or bad news? Why?

The deep fault has moved an inch a year, and the surface was supposed to have moved 300 in/25 ft but it hasn’t. This puts a lot of strain on the rocks underneath (which is granite aka very brittle) since a major quake hasn’t occurred in the last 300 years.