Geology Study Guide

Alfred Wegener proposed the theory of continental drift in the early 20th century, suggesting that continents were once joined together as one supercontinent called Pangaea. The fit of the east coast of South America with the lower west coast of Africa was one of the key pieces of evidence supporting this theory.

Till is the correct answer as it specifically refers to unsorted material deposited by glacial ice. Moraine, erratic, and drumlin are also related to glacial deposits, but they do not specifically refer to unsorted material showing no stratification.

Striations are the specific term used to describe scratches or gouges cut into bedrock by glacial movement, while the incorrect answers do not accurately describe this geological phenomenon.

Till and striations are common indicators of glacial activity, as they are remnants left behind by the movement of glaciers. Sand dunes, volcanic eruptions, and coral reefs are typically not associated with glacial coverage.

During the Late Paleozoic era, North America was one of the primary locations where abundant swamps contributed to the formation of coal. While other continents may have also had coal-forming swamps during this time, North America is specifically recognized for its significant coal deposits from that period.

Wegener's continental drift theory was ahead of its time and lacked a mechanism to explain how continents could move. Without a solid explanation, American geologists at the time were hesitant to accept his idea despite some compelling evidence from different fields of study.

The presence of coal in a cold, snowy location suggests that the area was once covered with swamps and/or jungles where plant material accumulated and eventually turned into coal over millions of years.

Striations on bedrock surfaces and poorly sorted sediment are indicative of glaciation, as glaciers are responsible for scratching the bedrock and depositing unsorted sediment as they move.

The term for the north (or south) magnetic pole's movement over time is known as polar wander.

An ordinary compass points towards magnetic north, which is not the same as true north, south, or east.

The correct answer highlights the fact that Earth's magnetic field has undergone reversals in polarity, which is evidenced by remnant magnetization in rocks. The incorrect answers provide misleading information that does not align with the scientific understanding of the Earth's magnetic field.

Seafloor spreading is the process where new oceanic crust is formed at mid-ocean ridges as tectonic plates move apart.

Seafloor spreading primarily occurs at divergent boundaries where tectonic plates move apart. Convergent boundaries involve plates moving towards each other, transform boundaries involve plates sliding past each other, and collision boundaries involve plates colliding with each other.

Seafloor spreading was a key piece of evidence that supported the theory of continental drift, explaining how continents move on Earth's surface.

Seafloor spreading occurs along mid-ocean ridges where tectonic plates are moving apart, allowing magma to rise up and solidify, creating new crust.

Seafloor spreading occurs at mid-ocean ridges where tectonic plates move apart, while subduction occurs at convergent plate boundaries where one plate is forced beneath another. The rates of these two processes do not align.

Marine magnetic anomalies are a result of changes in Earth's magnetic field that are recorded in the oceanic crust. By studying these anomalies, scientists can estimate the rate of seafloor spreading, which is the process by which new oceanic crust is formed at mid-ocean ridges. The other options are not directly estimated using marine magnetic anomalies.

Younger oceanic crust tends to accumulate carbonate ocean sediments due to the presence of more effective carbonate-producing organisms, while older oceanic crust accumulates silicic oceanic sediments as a result of increased weathering and erosion processes over time.

Seafloor spreading was supported by multiple lines of evidence including paleomagnetic striping, age progression of the ocean floor, and the presence of pillow basalts. However, high heat flow at mid-ocean ridges was not one of the pieces of evidence used.

Plate tectonics is the scientific theory that describes the large-scale motion of Earth's lithosphere. Continental drift is a phenomenon related to the movement of continents, not the lithosphere itself. The Earth's mantle is a layer beneath the lithosphere and is not directly related to the movement of tectonic plates. Continental collision refers to the collision of tectonic plates, which is a part of plate tectonics theory.

Continental lithosphere is typically thicker than oceanic lithosphere due to differences in composition and geological processes.

Plate tectonics refers to the theory that Earth's lithosphere is divided into large, rigid plates that float on the semi-fluid asthenosphere below. These plates move and interact with each other, leading to various geological phenomena such as earthquakes, volcanic activity, and mountain formation.

The lithosphere is rigid and solid, while the asthenosphere is capable of flowing over extended periods of time due to its semi-fluid nature. The asthenosphere plays a significant role in the movement of tectonic plates.

At a subduction zone, the down-going plate is typically oceanic lithosphere due to its higher density compared to continental lithosphere. Sedimentary rocks and volcanic ash are not typically involved in the subduction process.

Earthquakes are the primary indicators of boundaries between tectonic plates due to the movement and collision of these plates.

The abyssal plain is a flat and featureless region of the deep-ocean floor, characterized by sediments that have accumulated over thousands of years. Mid-ocean ridges are underwater mountain ranges, trenches are deep depressions in the ocean floor, and seamounts are underwater mountains that rise from the seafloor.

The majority of the continental crust is made up of rocks with a composition similar to granite, hence granite is the correct answer.

Oceanic crust is primarily composed of basalt, which is a dark, fine-grained volcanic rock. Granite, limestone, and quartz are not typical components of oceanic crust.

As new oceanic crust forms at mid-ocean ridges and moves away from the ridge due to plate tectonics, it accumulates more age over time. Therefore, the age of oceanic crust increases with distance from the mid-ocean ridge.