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Explainer: Earth’s Tectonic Plates

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explaining tectonic plate theory

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Explainer: Earth’s Tectonic Plates

It’s widely understood that Earth’s lithosphere (or outer crust) is made up of moving slabs of rock, better known as the tectonic plates.

These plates only move a couple of inches each year. However, these tiny movements add up over time and cause some of Earth’s most well-known phenomena. Today, the Earth looks a lot different than it did millions of years ago.

This graphic by Giulia De Amicis provides a brief explanation of plate tectonic theory and shows a map of the seven major plates.

Plate Tectonic Theory

In the early 20th century, German geologist Alfred Wegener published a paper on his theory called continental drift—a hypothesis that Earth’s continents were moving across Earth, and sometimes, even colliding into one another.

According to Wegener’s theory, Earth’s continents were once joined as a single, giant landmass, which he called Pangaea. But over time, Pangaea broke apart and formed the continents as we know them today.

Wegener couldn’t explain why this phenomenon was happening, so at the time, his theory was heavily criticized by his colleagues. But over the years, technological advances allowed scientists to study the Earth more closely, and geologists started to build on Wegener’s theory.

Discoveries like seafloor spreading helped explain the “why” behind continental movement, and eventually, Wegener’s initial continental drift theory morphed into plate tectonic theory. And now, the idea that Earth’s crust is slowly moving beneath our feet is widely accepted.

The Seven Major Tectonic Plates

There are seven major plates, and dozens of minor plates, that make up the outer crust of the Earth. The big seven are:

  • North American plate
  • Eurasian plate
  • Pacific plate
  • South American plate
  • African plate
  • Indo-Australian plate
  • Antarctic plate

The areas between these plates are known as plate boundaries, and their interactions cause some crazy things to happen on Earth’s surface. There are three types of plate boundaries:

1. Divergent boundary

A divergent boundary is when two plates move away from each other, which creates a fracture in the lithosphere.

A well-known divergent boundary is the Mid-Atlantic Ridge, which runs approximately 10,000 miles from the Arctic Ocean all the way down to the south of Africa.

2. Convergent boundary

A convergent boundary is when two plates collide with one another.

If the collision is between oceanic crust and continental crust, the denser oceanic crust slides underneath the other plate, which is a process known as subduction.

When two continental crusts collide, the rock folds and lifts at the boundary, creating mountains like the Himalayas (where the Indian plate meets the Eurasian plate).

3. Transform Boundary

When two plates move parallel to one another, their meeting point is called a transform boundary.

The friction causes tension. Eventually, that tension needs to be released, which can cause earthquakes. The San Andreas Fault is a well-known major transform boundary between the North American and Pacific plates—it caused the infamous San Francisco earthquake of 1906.

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This article was published as a part of Visual Capitalist's Creator Program, which features data-driven visuals from some of our favorite Creators around the world.

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Misc

Ranked: America’s Best Universities

Evaluated on 19 different metrics, here’s the list of America’s best universities, led by 14 private schools.

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Ranked: America’s Best Universities

The latest ranking of America’s best universities is here, perfectly timed for the approaching admissions season.

“Best” is of course subjective, and U.S. News and World Report has compiled 19 metrics on which they evaluated more than 400 national universities. Some of them include:

  • Graduation rates & performance: A four-year rolling average of the proportion of each entering class earning a bachelor’s degree in six years or less. Performance is measured against predictions made by the publishers, and when beaten, the university gains a higher scoring.
  • Peer assessment: A two-year weighted average of ratings from top academics—presidents, provosts and deans of admissions—on academic quality of peer institutions with which they are familiar.
  • Financial resources: The average per student spend on instruction, research, student services and related educational expenditures in the 2021 fiscal year.
  • Debt: A school’s average accumulated federal loan debt among borrowers only.
  • Pell graduation rates & performance: the same calculation as stated above, but focused only on Pell Grant students, adjusted to give more credit to schools with larger Pell student proportions.

The website’s methodology section details how they sourced their data, the weights assigned to each metric, and their changes over the years.

From the hundreds assessed come the nearly 50 best universities that offer a variety of undergraduate majors, post-graduate programs, emphasize research, or award professional practice doctorates.

Which are the Best Universities in America?

At the top of the list, Princeton University is the best university in the country, known for its physics, economics, and international relations departments. Notably, it’s a rare Ivy league university that does not have a law, medical, or business school.

Here’s the full ranking of America’s best universities, along with annual tuition requirements.

RankSchool NameStateTuition
1Princeton UniversityNew Jersey$59,710
2Massachusetts
Institute of
Technology
Massachusetts$60,156
3Harvard UniversityMassachusetts$59,076
3Stanford UniversityCalifornia$62,484
5Yale UniversityConnecticut$64,700
6University of
Pennsylvania
Pennsylvania$66,104
7California Institute
of Technology
California$63,255
7Duke UniversityNorth Carolina$66,172
9Brown UniversityRhode Island$68,230
9Johns Hopkins
University
Maryland$63,340
9Northwestern UniversityIllinois$65,997
12Columbia UniversityNew York$65,524
12Cornell UniversityNew York$66,014
12University of ChicagoIllinois$65,619
15University of
California, Berkeley
California$48,465 (out-state)
$15,891 (in-state)
15University of
California, LA
California$46,326 (out-state)
$13,752 (in-state)
17Rice UniversityTexas$58,128
18Dartmouth CollegeNew Hampshire$65,511
18Vanderbilt UniversityTennessee$63,946
20University of Notre DameIndiana$62,693
21University of
Michigan, Ann Arbor
Michigan$57,273 (out-state)
$17,786 (in-state)
22Georgetown UniversityWashington, DC$65,082
22University of North
Carolina at Chapel Hill
North Carolina$39,338 (out-state)
$8,998 (in-state)
24Carnegie Mellon UniversityPennsylvania$63,829
24Emory UniversityGeorgia$60,774
24University of VirginiaVirginia$58,950 (out-state)
$22,323 (in-state)
24Washington
University, St. Louis
Missouri$62,982
28University of
California, Davis
California$46,043 (out-state)
$15,266 (in-state)
28University of
California, San Diego
California$48,630 (out-state)
$16,056 (in-state)
28University of FloridaFlorida$28,658 (out-state)
$6,381 (in-state)
28University of
Southern California
California$68,237
32University of
Texas, Austin
Texas$41,070 (out-state)
$11,698 (in-state)
33Georgia Institute
of Technology
Georgia$32,876 (out-state)
$11,764 (in-state)
33University of
California, Irvine
California$47,759 (out-state)
$15,185 (in-state)
35New York UniversityNew York$60,438
35University of
California, Santa
Barbara
California$45,658 (out-state)
$14,881 (in-state)
35University of Illinois
Urbana-Champaign
Illinois$36,068 (out-state)
$17,572 (in-state)
35University of
Wisconsin, Madison
Wisconsin$40,603 (out-state)
$11,205 (in-state)
39Boston CollegeMassachusetts$67,680
40Rutgers University,
New Brunswick
New Jersey$36,001 (out-state)
$17,239 (in-state)
40Tufts UniversityMassachusetts$67,844
40University of WashingtonWashington$41,997 (out-state)
$12,643 (in-state)
43Boston UniversityMassachusetts$65,168
43The Ohio State UniversityOhio$36,722 (out-state)
$12,485 (in-state)
43Purdue University,
Main Campus
Indiana$28,794 (out-state)
$9,992 (in-state)
46University of
Maryland, College
Park
Maryland$40,306 (out-state)
$11,505 (in-state)
47Lehigh UniversityPennsylvania$62,180
47Texas A&M UniversityTexas$40,607 (out-state)
$12,413 (in-state)
47University of GeorgiaGeorgia$30,220 (out-state)
$11,180 (in-state)
47University of RochesterNew York$64,384
47Virginia TechVirginia$36,090 (out-state)
$15,478 (in-state)
47Wake Forest UniversityNorth Carolina$64,758
53Case Western
Reserve University
Ohio$62,234
53Florida State UniversityFlorida$21,683 (out-state)
$6,517 (in-state)
53Northeastern UniversityMassachusetts$63,141
53University of
Minnesota, Twin
Cities
Minnesota$36,402 (out-state)
$16,488 (in-state)
53William & MaryVirginia$48,841 (out-state)
$25,041 (in-state)

MIT places second, and Harvard and Stanford tie for third. Yale rounds out the top five.

Private universities, including seven Ivy League colleges, dominate the top of the rankings. Meanwhile, the highest-ranked public schools are tied at 15th, both state schools in California.

For affordability, since the higher ranks are populated by private universities, there tends to be a broad correlation of better universities being more expensive. That said, the most expensive school in the top 50 ranks is actually the University of Southern California, tied at 28th, for $68,237/year.

As it happens, also tied at 28th, the University of Florida is the most affordable public school for in-state students ($6,381/year) and Florida State University tied at 53rd, is the most affordable for out-of-staters at $21,683/year.

However these costs are tuition-only, and don’t account for other necessary expenses: accommodation, food, and textbooks.

Best University versus Best “Fit”

Finding the best university for prospective students is more than just perusing a long ranking list.

Aside from the numerous schools present within each university—which can often be the best for specific majors—factors like location, proximity to family, campus culture, the non-academic pursuits (sports, extracurriculars, internships) are also taken into consideration.

In fact, research has found that just attaining a university degree improves future earnings potential and employability.

Furthermore, individual engagement at college (irrespective of the rank of the school in question) plays a far bigger role in learning and general well-being than simply attending a highly-ranked school.

However, for low income and minority students, attending a top-ranked school does improve future earnings considerably. For women, it also often results in delaying marriage and kids, which results in more work-hours and as a result, more pay.

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