The main types of mountains — Earth’s ups and downs

Mountains have always played a central role in human culture, but we’ve only recently come to understand how they form and develop. To this day, these magnificent landforms still hold many secrets. There are several ways to analyze and classify mountains depending on your scientific discipline. Here, we’ll describe some of the more common classifications of mountains in detail.

Aerial view of Mount Everest from the south. The Himalayas are fold mountains. Image credits: airline company Drukair in Bhutan.

The Types of Mountains

Generally, mountains be classified as: fold mountains, block mountains, dome mountains, and volcanic mountains. Plateau mountains, uplifted passive margins, and hotspot mountains are also sometimes considered.

  • Fold mountains — the most common type, they form when two or more tectonic plates collide.
  • Block mountains (or fault-block) — formed through geological processes pushing some rocks up and others down.
  • Dome mountains — formed as a result of hot magma pushing beneath the crust.
  • Volcanic mountains — also known by a simpler name: volcanoes.
  • Other types of mountains sometimes included in classifications are plateau mountains, uplifted passive margins, and hotspot mountains.

Fold mountains

The Rocky Mountains are a great example of fold mountains. Image credits: National Park Service Digital Image Archives.

Fold mountains are the most common and most massive types of mountains (on Earth, at least). Fold mountain chains can spread over thousands of kilometers — we’re talking about the Himalayas, the Alps, the Rockies, the Andes — all the big boys. They’re also relatively young (another reason they’re so tall, as they haven’t been thoroughly eroded), but that’s “young” in geological terms — still tens of millions of years.

In order to understand how fold mountains form and develop, we have to think about plate tectonics. The Earth’s lithosphere is split into rigid plates which move independently of one another. There are seven major tectonic plates and several smaller ones all across the world.

When two plates collide, several things can happen. For instance, if one plate is denser than the other (oceanic plates are typically denser because of the type of rocks that make up the plate), a process called subduction will start: the heavier one will slowly glide beneath the lighter one. If they have relatively similar densities, then they will start to crumple up, driving movement upwards. Essentially, the tectonic plates are pushed, and since neither can slide beneath the other, they build up geological folds. To get a better idea of what this looks like, try to push two pieces of papers towards each other: some parts will rise up, representing the process of mountain formation.

Sometimes, the folding happens inside the continent and is associated with faulting. This is a representation of that process in northern Montana, USA, and Southern Alberta, Canada. Image credits: Greg Beaumont, National Park Service.

This process is called orogeny (giving birth to mountains) and it generally takes millions of years for it to complete. Many of today’s fold mountains are still developing as the tectonic process unfolds. The process doesn’t occur on tectonic edges — sometimes the mountain-generating fold process can take place well inside a tectonic plate.

Block mountains (or fault-block)

While the previous category was all about folds, this one is all about faults: geological faults, that is.

Depiction of the block-faulting process. Image credits: U.S. Geological Survey.

Let’s revisit the previous idea for a moment. Let’s say that while under pressure, some parts of a tectonic plate start to fold. As the pressure grows and grows, at one point the rock will simply break. Faults are those breaks: they’re the planar fractures or discontinuities in volumes of rock. Their size can vary tremendously, from a few centimeters to mountain-sized.

Basically, when big blocks of rock are broken through faulting, some of them can get pushed up or down, thus resulting in block mountains. Higher blocks are called horsts and troughs are called grabensTheir size can also be impressive, though they’re generally not as big as fold mountains because the process which generates them takes place on a smaller scale and involves less pressure. Still, the Sierra Nevada mountains (an example of block mountains), feature a block 650 km long and 80 km wide. Another good example is the Rhine Valley and the Vosges mountain in Europe. Rift valleys can also generate block mountains, as is the case in the Eastern African Rift.

Mount Alice and Temple Crag in the Sierra Nevada. Image credits: Miguel.v

It can be quite difficult to identify a block mountain without knowing its underlying geology but generally, they tend to have a steep side and a slowly sloping side.

Volcanic mountains

Annotated view includes Ushkovsky, Tolbachik, Bezymianny, Zimina, and Udina stratovolcanoes of Kamchatka, Russia. Image taken aboard the ISS in 2013.

Everyone knows something about volcanoes, though we rarely think about them as mountains (and truth be told, they aren’t always mountains).

Volcanic mountains are created when magma deep beneath the surface starts to rise up. At one point, it erupts in the form of lava and then cools down, solidifying and piling on to create a mountain. Mount Fuji in Japan and Mount Rainier are classic examples of volcanic mountains — with Mount Rainier being one of the most dangerous volcanoes in the world. However, it’s not necessary for the volcano to be active to be a volcanic mountain.

The summit of Mauna Kea. Image credits: Pixabay.

Several types of volcanoes can generate mountains, with Stratovolcanoes typically creating the biggest ones. Despite the fact that Mount Everest is the tallest mountain above sea level, Mauna Kea is actually much taller than Everest at a total height over 10,000 meters. However, much of it is submerged, with only 4,205 meters rising above sea level.

Dome mountains

Dome mountains are also the result of magmatic activity, though they are not volcanic in nature.

Southeast face of Fairview Dome in Yosemite National Park. Image credits: Jennie.

Sometimes, a lot of magma can accumulate beneath the ground and start to swell the surface. Occasionaly, this magma won’t reach the surface but will still form a dome. As that magma cools down and solidifies, it is often tougher than other surrounding rocks and will eventually be exposed after millions of years of erosion. The mountain is this dome — a former accumulation of magma which cooled down and was exposed by erosion.

Round Mountain is a relatively recently formed dome mountain. It represents a volcanic feature of the Canadian Northern Cordilleran Volcanic Province that formed in the past 1.6 million years. Black Dome Mountain is another popular example, which is also located in Canada.

Other types of mountains

As we mentioned above, there’s no strict definition of mountain classifications, so other types are sometimes mentioned.

Plateau mountains

Plateau mountains aren’t formed by something going up — they’re formed by something going down. For instance, imagine a plateau that has a river on it. Year after year, that river carves out a part of the plateau, bit by bit. After some time, there might only be a small part of the original plateau left un-eroded, which basically becomes a mountain. This generally takes a very long time even by geological standards, taking up to billions of years. Some geologists group these mountains with dome mountains into a broader category called erosional mountains.

Uplifted passive margins

There’s no geological model to fully explain how uplifted passive margins formed, but we do see them in the world. The Scandinavian Mountains, Eastern Greenland, the Brazilian Highlands or Australia’s Great Dividing Range are such examples, owing their existence to some uplifting mechanism.

Hotspot mountains

The trail of underwater mountains created as the tectonic plate moved across the Hawaii hotspot over millions of years. Image credits: USGS.

Although once thought to be identical to volcanic mountains, new research has shed some light on this belief. Hotspots are volcanic regions thought to be fed by a part of the underlying mantle which is significantly hotter than its surroundings. However, even though that hot area is fixed, the plates move around it — causing it to leave a hotspot trail of mountains.

11 thoughts on “The main types of mountains — Earth’s ups and downs

  1. agelbert

    Great article! I know that it is very controversial in main stream academic geology circles, but what do you think of the theory of global expansion causing mountain formation as the surface of the sphere becomes less curved. There is indisputable geologic evidence that all the ocean basins are much younger than the earth's crust on continents. Tectonic plate theory does not have an answer to that but the expanding earth theory fits the planetary geology much better. I am not saying that plate tectonics are not involved in mountain formation; I am saying that an expanding globe combined with plate tectonics is a more comprehensive theory of our geology.

  2. Andrei Mihai

    I'm not particularly familiar with this theory, but the tectonic mechanism of orogeny is pretty well established.

  3. agelbert

    Well, the maximum age of the ocean basins is about 190 million years. But the thing that is most convincing to me that something besides plate tectonics is at work is the distance of the oceanic rifts from the land masses of Australia and Antarctica. It makes no sense UNLESS they stretched apart without any subduction whatsoever.

    Also, the closer you get to the oceanic volcanic ridges, the younger the crust is. Finally the crust of the earth is thinner in the ocean basins than on continents. All of that argues for global expansion.

    I know you will think this unscientific, but I am familiar with stretch marks on human female breasts when they grow too quickly for the skin to adjust normally. The ocean basin topography looks uncannily like these types of stretch marks. But the stretching of landscape on land is a known geologic feature that also appears to be identical, though in much smaller scale to the oceanic "stretch mark" like topography.

    Please watch the video and tell me what you think is inaccurate about global expansion theory.

  4. Andrei Mihai

    I do think this is pretty unscientific, yes. I'll agree that plate tectonics is not a perfect, all-encompassing theory. It's an area of active research, and the sheer complexity of the subject will have us learning new things years and years from now… but.

    The video starts from some truthful, and some false premises. For instance, the oldest oceanic crust isn't 140 million years old. In the west Pacific and north-west Atlantic, oceanic crust is 180-200 million years old. These are pretty big areas, not isolated patches, but it gets even better. In the Eastern parts of the Mediterranean, there are remnants of the former Tethys Ocean, which are 270 million years old (some studies put bits of it at 340 million years old). This is the most commonly referenced map, which I recommend having a look at.

    There's a mountain of evidence supporting plate tectonics, so we know it's happening, it's very much real, though we're not exactly sure what's the exact mechanism of movement, and how all of it happens. This is always the case when you're studying phenomena on this scale, and working only with indirect evidence. As for the disappearance of plates, look up subduction. Oceanic plates are denser and "heavier" than continental plates, which is why they tend to subduce and get consumed in the litosphere.


  5. agelbert

    Thank you for your polite and respectful response. It is rare to see an erudite person like yourself treat a person who is not credentialed this way. So, I am grateful for this conversation with you.
    I respect your opinion, and that of the geologic mainstream scientific community. I agree with you that more research and experimentation is required to fully understand plate tectonics.
    The only question I have, judging for your comment about the ocean basin age mentioned in the video, is why you didn't watch the full video. The different ocean basin age crusts was explained in detail, along with a discussion of the Mediterranean Sea basin.
    I have studied subduction theory. I remain unconvinced that such crustal "conveyer belt" actually exists simply because of the nearly equidistant volcanic rifts from the continental plates on either side in the Atlantic Ocean and between Australia and Antarctica.
    Furthermore, subduction is a rather convenient excuse to claim that ocean basin crust is "reformed" with such high temperatures that it age simply "appears" to be much younger than the 4.5 billion year, much older dated continental land areas. The 4.5 billon year dating versus the age much younger age for ocean basins as you stated, citing a maximum of 340 million years for one basin age versus 190 million years for others (with various documented ages in between), is not explained by subduction theory.
    I am of the belief that the dating methods used by geologists are accurate, at least within an error margin of 100 million years.
    So, the gigantic gap between continents and ocean basin problem remains to be answered.

  6. agelbert

    If the Mckenzie model works for continental crust, why isn't it also clear that the same mechanism is at work in oceanic basin crust (i.e. stretching from expansion, not contraction)?

    Well, it is clear to the geologists. But that's where the controversy begins as to the CAUSE of that indisputable evidence of stretching.

    In the graphic below, accepted by mainstream geologists, the stretching of the ocean basins is not in question. They admit that the basins are stretching; they simply require the subduction theory to explain that crustal stretching in order to avoid dealing with the ocean basin stretching based evidence of global expansion.

    And as to crustal compression, as alleged to be the cause of continents moving towards one another, thereby causing mountain ranges to be formed, a less curved sphere of the earths surface, the result of an expanding globe, is a better explanation of how absolutely every mountain range on earth was formed. Just look, with unbiased eyes, at the location of mountain ranges and you will see what I mean.

    Mountain range creation can be modeled on a tiny scale by arcing a 4' by 8' piece of plywood, fixing it in position, and applying plaster of Paris at varying thicknesses over it. After the plaster is hard in a day or so, gradually reduce the curvature and observe the "crustal compression", NOT from "continental plate collisions", but from a less curved surface.

    This effect can also be observed in an inflated balloon covered with mud that is allowed to dry. When the balloon is further inflated the compression of the mud to form miniature "mountain ranges" and "ocean basins, where the added balloon area appears, is obvious to anyone but a mainstream geologist.
    I think they are just stubborn and set in their ways. But someday the obvious reality of an expanding globe will be accepted over the convenient theory of subduction, invented to avoid accepting the reality of an expanding globe.

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