Which of the following pieces of evidence supports the plate tectonic theory?
A. Ocean-floor sediments are oldest at the ridge crest.
B. The stripe patterns of high- and low-intensity magnetism are mirror images on both sides of an oceanic ridge.
C. Ocean-floor sediments are thickest at the ridge crest.
D. The youngest volcanoes in the Hawaiian Island-Emperor Seamount chain are at Suiko Seamount, near the Aleutian Islands.
E. The volcanoes that make up the Hawaiian Island chain are the same age.
Well, well, look at all these options trying to impress us with their evidence for the plate tectonic theory! Let's break them down with some humor, shall we?
A. Ocean-floor sediments are oldest at the ridge crest. Well, that's quite a strange way to show support! It's like saying the oldest food is found on top of the birthday cake. Not the best evidence, if you ask me.
B. The stripe patterns of high- and low-intensity magnetism are mirror images on both sides of an oceanic ridge. Ah, magnetism playing dress-up with its mirror image! It's like a cosmic game of matching outfits. At least this one seems more legit!
C. Ocean-floor sediments are thickest at the ridge crest. Hmmm, thick sediments at the ridge crest? It's like wearing your thickest coat at the beach. Doesn't make much sense, does it?
D. The youngest volcanoes in the Hawaiian Island-Emperor Seamount chain are at Suiko Seamount, near the Aleutian Islands. Oh, those sneaky little volcanoes playing "Who's the Youngest?" Okay, this is a bit more convincing. It's like finding out the newest superhero movie is playing at the cinema near your place.
E. The volcanoes that make up the Hawaiian Island chain are the same age. Ah, the Hawaiian Island chain, a true fountain of youth for volcanoes! Like a group of friends who refuse to grow old together. Remarkable!
So, after all the joking around, it seems like options B and D provide stronger support for the plate tectonic theory. Magnetism playing dress-up and volcanoes having a competition for the youngest title. Quite the amusing evidence, don't you think?
The correct answer is:
B. The stripe patterns of high- and low-intensity magnetism are mirror images on both sides of an oceanic ridge.
This evidence supports the plate tectonic theory because it suggests that the seafloor is spreading apart at mid-ocean ridges, with new crust forming on either side. As the molten rock cools and solidifies, the magnetic minerals align with the Earth's magnetic field, creating a pattern of alternating high- and low-intensity magnetism. The fact that these patterns are mirrored on both sides of an oceanic ridge suggests that the seafloor is spreading apart symmetrically.
To determine which of the pieces of evidence supports the plate tectonic theory, we can examine each option and see how it relates to the fundamental concepts of plate tectonics.
A. Ocean-floor sediments are oldest at the ridge crest: This observation supports the plate tectonic theory. At mid-ocean ridges, where new oceanic crust is formed, the crust gets progressively older as you move away from the ridge crest. This is because the new magma from the mantle solidifies at the ridge crest and forms new oceanic crust, pushing the older crust away from the center. The observation of oldest sediments at the ridge crest aligns with this concept.
B. The stripe patterns of high- and low-intensity magnetism are mirror images on both sides of an oceanic ridge: This observation also supports the plate tectonic theory. Earth's magnetic field has reversed its polarity numerous times in the past. As new oceanic crust forms at mid-ocean ridges, it records the prevailing magnetic field at the time. The pattern of normal and reversed magnetic polarities can be observed as symmetrical stripes on both sides of an oceanic ridge, indicating the spreading of the oceanic plates.
C. Ocean-floor sediments are thickest at the ridge crest: This observation is not directly related to plate tectonics. The thickness of sediments can be influenced by various factors, including the rate of sedimentation and local geologic conditions. While the formation of new oceanic crust at the ridge may contribute to sediment accumulation, the thickness of sediments alone does not provide conclusive evidence for plate tectonics.
D. The youngest volcanoes in the Hawaiian Island-Emperor Seamount chain are at Suiko Seamount, near the Aleutian Islands: This observation is not directly related to plate tectonics. The Hawaiian Island-Emperor Seamount chain is formed by a hotspot, where a stationary plume of hot mantle material rises to the surface. The motion of tectonic plates over the hotspot creates a chain of progressively older volcanoes. While this evidence supports the existence of plate motion, it does not specifically support plate tectonics.
E. The volcanoes that make up the Hawaiian Island chain are the same age: This observation does not support plate tectonics. As mentioned earlier, the Hawaiian Island-Emperor Seamount chain is formed by the movement of tectonic plates over a hotspot. The age of the volcanoes in the chain progressively increases as you move away from the hotspot. Therefore, the fact that the volcanoes are the same age indicates volcanic activity rather than plate tectonics.
Based on the analysis, options A and B are the pieces of evidence that support the plate tectonic theory, while options C, D, and E are not directly related or do not specifically support plate tectonics.