The goal of this essay is to investigate the depths between sedimentary and igneous rocks through the research question, “Are sedimentary rocks always found below igneous rocks?” and the claim “Sedimentary rocks are always found below the other rock types” There are three main types of rocks found on the Earth (Sedimentary, Igneous and Metamorphic), this essay will mainly focus on Sedimentary and Igneous rocks. Sedimentary rocks are formed when small fragments of the rock travel to a different location through wind, water or any other activity. The fragments from weathering of older rocks compact and compress through the cementation process and forms a sedimentary rock (Keith A.W. Crook, Kevin Charles Beck, Harold J. Bissell, 2023). Whereas, igneous rocks are formed when magma cools and crystallises. (Dodd, How are Igneous Rocks formed?, 2020).
To investigate the depth of sedimentary and igneous rocks, the Research Question ‘Are sedimentary rocks always found below igneous rocks?’ was formulated. Clear patterns emerge through the analysis of the Strati-graph. Since newer and higher rocks are exposed to winds more directly than lower rocks, it can be interpreted that the angular shape of a mountain is caused. Limestone is found at the highest layer of the mountain and also the lowest layer near the valley. The rocks near the Colorado river are older i.e., Proterozoic era (541 million-2.5 billion years old). The Proterozoic era contains mainly granite (Igneous) and schist (Metamorphic). Whereas sedimentary rocks are primarily found in the Paleozoic era (~252-541 million years old). Therefore, the claim that sedimentary rocks are always found below igneous rocks can be disproved.
To address the research question, several sources were analysed and interpreted. One of them being the well-known organisation, National Geographic. Igneous rocks fall into two different classifications, extrusive and intrusive. Extrusive rocks are found on the surface of the Earth, whereas intrusive rocks are found within the Earth (National Geographic “Igneous Rocks” 2022). This source provides evidence to address the research question by giving us evidence of how deep igneous rocks are located. It can be interpreted those igneous rocks are located at various depths under the Earth and on the surface of the Earth as well. This further disproves the claim of sedimentary rocks being found below other types of rocks.
Another source used for research the article “Sedimentary vs Igneous: Differences and Similarities” published by How to Find rocks. Sediments are deposited in low-lying areas and can extend for a few thousand kilometers. Successive depositional events, which can take millions of years, produce layers called beds, strata, or stratification. Whereas, Igneous rocks are mainly crystalline. Magma that cools at a great depth form bodies of rocks called intrusive bodies or plutonic bodies called plutons. In relatively shallow environments (How to Find Rocks “Sedimentary vs Igneous: Differences and Similarities” 2021). It can be interpreted that most igneous rocks are mainly crystals and are found at great depths. Whereas, sedimentary rocks are usually found on the surface of the Earth through compaction of sediments. The claim can be directly refuted again from the research showing sedimentary rocks not always being found under igneous rocks.
There are many limitations that restricted answering the research question. For example, figure 1 helped identify the rock age and depths, but that diagram was only limited to the Grand Canyon. Another source used was National Geographic, though it was useful to understand sedimentary and igneous rocks, it was very brief on the depths of each rock types. Britannica was also used to study both, sedimentary and igneous rocks. It was beneficial to understand how each rock was found but was also very brief on the depths of each rock type. HowToFindRocks was also used to identify similarities and differences between sedimentary and igneous rocks, but this source was limited to the understanding of an independent researcher and didn’t explain the depths of each rock types.
Based on the analysis of “Are sedimentary rocks always found below igneous rocks?” The question can be refuted and disproved. The key pieces of evidence that supported this conclusion was found in figure 1 that showed igneous rocks older than sedimentary rocks, therefore, it can be interpreted that sedimentary rocks aren’t always found under igneous rocks. By answering the research question this way, the claim can be addressed. It can be concluded that sedimentary rocks aren’t always found below igneous rocks since most igneous rocks are older than sedimentary rocks.
References & Further Readings
Dodd, C. (2020, October 22). How are Igneous Rocks formed? Retrieved from World Atlas: https://www.worldatlas.com/articles/how-are-igneous-rocks-formed.html
Dodd, C. (2020, August 15). How are Sedimentary rocks formed? Retrieved from World Atlas: https://www.worldatlas.com/articles/how-are-sedimentary-rocks-formed.html
John. (2021, May 15). Sedimentary vs. Igneous Rocks: Differences & Similarities. Retrieved from How to FInd Rocks: https://howtofindrocks.com/sedimentary-vs-igneous-rocks/
Keith A.W. Crook, Kevin Charles Beck, Harold J. Bissell. (2023, May 17). sedimentary rock. Retrieved from Britannica: https://www.britannica.com/science/sedimentary-rock
National Geographic Society. (2022, July 16). Igneous Rocks. Retrieved from National Geographic: https://education.nationalgeographic.org/resource/igneous-rocks/
National Geographic Society. (2022, July 16). Rock Cycle. Retrieved from National Geographic: https://education.nationalgeographic.org/resource/rock-cycle/
National Geographic Society. (2022, July 16). Sedimentary Rocks. Retrieved from National Geographic: https://education.nationalgeographic.org/resource/sedimentary-rock/
stratigraphy. (n.d.). Retrieved from Britannica: https://cdn.britannica.com/86/106986-050-0119C0F2.jpg
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