lesson 2: theory of continental drift

Question 1

abraham ortelius

Answer 1

• 1596
• Cartographer
• He is recognized as the creator of the first modern map, the Theatrum Orbis Terrarum

Question 2

Antonio Snider-Pellegrini

Answer 2

• 1858
• geographer
• scientist
• theorized about the possibility of continental drift

Question 3

Alfred Wegner

Answer 3

• 1912
• Championed the concept of the continental drift based upon his study of similar rock types
• He used fossil evidence
• He theorized that the Mid-Atlantic Drift continuously tears apart, causing hot, relatively fluid material settles on top of the crust, creating a new oceanic crust
• He noticed the similarity in the coastlines of eastern South America and western Africa (and Australia) and speculated that those continents had once formed a supercontinent, Pangaea, which had split and slowly moved many km’s apart over time.
• He also pointed to closely related fossil organisms and similar rock strata that occurred on widely separated continents.

Question 4

Harold Jefferey’s

Answer 4

1926
* A liquid core was determined by Harold Jefferey’s, aided by the discovery of radiation
* Geophysicist
* he investigated the thermal history of the Earth, was coauthor of the standard tables of travel times for earthquake waves and was the first to demonstrate that the Earth’s core is liquid. He explained the origin of monsoons and sea breezes and showed how cyclones are vital to the general circulation of the atmosphere. Jeffreys also published seminal works on probability theory and on methods of general mathematical physic

Question 5

Arthur Holmes

Answer 5

• 1927
• geologist
• He was the first earth scientist to grasp the mechanical and thermal implications of mantle convection, and he widely applied the newly-developed method of radioactive dating to minerals in the first attempt to quantitatively estimate the age of the Earth.

Question 6

Marie Tharp

Answer 6

• 1953
• discovered the 10,000-mile-long Mid-Atlantic Ridge —a find that showed that the sea floor was spreading
• Tharp made a map that vindicated the controversial theory of plate tectonics.

Question 7

Harry Hess

Answer 7

• 1962
• He copied Marie Tharp’s idea that the sea floor is created at spreading ridges, expanding on Alfred Wegner’s theory.
• He published theories on sea floor spreading, specifically on relationships between island arcs, seafloor gravity anomalies, and serpentinite peridotite, suggesting that the convection in the Earth’s mantle is the driving force behind this process

Question 8

extra notes

Answer 8

• Harry Hess proposed the theory of the seafloor spready based upon his evidence and maps of the seafloor topography indicating the existence of a world-wide mid-ocean ridge system
• He proposed that ridges are located above zones of upwelling in the mantle - resulting in the creating of the sea floor
• The magma, located in the mantle, heats up and the particles spread apart
• The closer the magma gets to the crust, the cooler it gets, causing the particles to come together again
• This cycle goes on. However, sometimes the magma gets caught between the tectonic plates, forming a new crust, and pushing the tectonic plates further apart

Question 9

palaeomagnetism

Answer 9

The Earth’s magnetic field produces invisible lines of force that extend from one pole to the other. A compass needle aligns itself with these lines of force-points towards the magnetic poles. When igneous rocks contained magnetic minerals crystallize, the crystals align themselves with the earth’s magnetic field. If the rock is moved, its magnetic field will function as a ‘fossil compass’. Magnetized minerals can also be used to determine the latitude of their origin. The Earth’s magnetic field is curved, and the inclination of the magnetic grains gives an estimate of the paleolatitude.

Question 10

equator

Answer 10

horizontal

Question 11

midaltitude

Answer 11

high angle

Question 12

pole

Answer 12

straight up or down

Question 13

Pole wandering

Answer 13

Looking at igneous rocks, the apparent position of the North pole was determined from the paleomagnetism of the rock. Assuming that the magnetic poles are approximately coincident with the pole of rotation, the apparent movement of the poles must be due to the movement of the continents. If the two continents are placed next to each other to how we believe they fit in Pangaea, the apparent pole wondering paths would coincide.

Question 14

sea floor spreading

Answer 14

Harry Hess proposed the theory of seafloor spreading based upon this evidence and newly published maps of the seafloor topography indicating the existence of a world-wide mid-ocean ridge system. He proposed that ridges are located above the zones of upwelling in the mantle, resulting in the creation of the sea floor. He also proposed subduction as a mechanism for the recycling of the seafloor. This supports the idea of the continental drifting as this provides the way in which the continents were able to separate