Exam 1 Flashcards
About ____% of Earth’s water is found in the ocean.
97%
On a planetary scale, the ocean comprises about ____% of Earth’s mass.
0.02
What comprises the most abundant form of matter in the universe?
hydrogen and helium
Stars spend their lives changing its hydrogen and helium to ____.
carbon, oxygen, silicon, and iron
What process allows the sun to generate light and heat?
accretion
Oxygen first began to accumulate in Earth’s atmosphere as a result of ____.
photosynthesis
Earth’s inner core is primarily made of ____.
iron
The primary physical process responsible for the formation of Earth’s layers, the inner and outer core, mantle, and crust is ____.
density stratification
Who was the first person to compile a picture of the large-scale wind and current systems?
Matthew Maury
The Challenger expedition (1872–1876) was a unique and historic voyage. Why?
It is the longest continuous scientific oceanographic expedition on record.
The ocean provides a variety of resources ranging from food and water to energy, construction materials, and life-saving pharmaceuticals.
True
Earlier than 200 million years ago, the continents were joined into one supercontinent called ____.
Pangaea
What is the primary reason for the inside of Earth being hot?
The decay of radioactive elements is creating heat in Earth’s inner layers.
The rigid outer layer of Earth that comprises the continental crust, oceanic crust, and the uppermost mantle is called the ____.
lithosphere
The mid-ocean ridges are ____.
divergent plate boundaries
California’s San Andreas fault is which type of plate boundary?
transform plate boundary
A “mystery” in our understanding of plate tectonics has been, until recently, the nature of the power source capable of moving the plates and the continents embedded within them. Recent evidence indicates the power source to be ____.
convection currents within Earth’s mantle moving the plates
If two oceanic plates collide and one is older and cooler (and therefore, denser) than the other, what will happen?
A deep trench will form
Which statement is true with regard to subduction zones?
They are zones where old seafloor descends into the crust and mantle.
Which statement about hot spots is true?
Hot spots arise from relatively stationary plumes of magma in the mantle.
The transition between the shelf and the deep seafloor is the ____.
continental slope and rise
Which statement accurately describes a turbidity current?
a fast, dense current of water and sediment that runs down slopes
Which statement accurately describes active continental margins?
They are areas of frequent earthquakes and volcanoes.
The deepest places in Earth’s crust are ____.
ocean trenches
The deep-ocean basin includes which of the following features?
abyssal plains
Which of the following is a major source of terrigenous sediments?
weathering and erosion of rocks
Over millions of years, natural gas and oil can be formed from ____.
biogenous sediments
Carbonate sediments are rare in deep sea sediments because the ____.
carbonate shells are dissolved in deep water
A cross section of Earth reveals a layered structure that has different thicknesses and densities. How do geologists know this?
from observing the transit times through Earth of seismic waves generated by earthquakes
The Himalayan Mountains were formed as a result of ____.
continent–continent convergence
Where would you look to find an ocean trench? How are these features related to plate tectonics?
Ocean trenches are the result of convergent boundaries. Specifically, they form along subduction zones where oceanic crust sinks under the continental one. Therefore, trenches are typically found in the deep-ocean floor of the Pacific, which is characterized by active margins.
What were the contributions of Captain James Cook? Does he deserve to be remembered more as an explorer or as a marine scientist?
James Cook can be considered both and explorer and marine scientist. He was a pioneer of modern oceanography because he described, recorded, and collected specimens of marine life, plants, and animals all around the world. In addition, he first found and charted New Zealand and the West Coast of North America, and mapped Australia’s Great Barrier Reef. He also was able to interpret events in natural history, anthropology, and oceanography.
Look again at Figure 2.21. Why do the dates go back only about 200 million years when we know the ocean has been on Earth for billions of years?
The oldest rock only goes back to 200 million years ago because that’s when the Pangaea started to split apart and form continental plates. The interaction between plates at plate boundaries then resulted in the subduction of older oceanic crust under the younger and lighter continental crust or younger oceanic crust.
List the four types of marine sediments. Explain the origin of each.
Terrigenous sediments: originate from the erosion of continents or islands, as well as volcanic eruptions and blown dust. It is considered one of the most dominant sediments, especially on continental margins and abyssal plains.
Biogenous sediments: originate from organic matter that comes from the marine organisms such as corals or shells of molluscs. It’s another dominant sediment.
Hydrogenous sediments: originate from the leaching of the crust at oceanic ridges and dissolved minerals coming from submerged rocks.
Cosmogenous sediments: originate from dust from space and meteorite debris. Therefore, it is found in really small proportion, usually mixed in with other, more dominant sediments.
