<p>Have you had a look at the northern coast of Russia or Alaska, in the cold Arctic? Having just looked at them on Google Earth, they are lengthy and seem very &quot;un-rugged&quot;.</p>
<p>The northern coast of Russia:</p>
<p><a href="https://i.sstatic.net/tRKxq.jpg" rel="noreferrer"><img src="https://i.sstatic.net/tRKxq.jpg" alt="Russia" /></a></p>
<p>The northern coast of Alaska:</p>
<p><a href="https://i.sstatic.net/d6zOH.jpg" rel="noreferrer"><img src="https://i.sstatic.net/d6zOH.jpg" alt="Alaska" /></a></p>
<p>Opposite of that, in the hot subtropical Australia, the Kimberley coast in the north western part of the continent looks rugged:</p>
<p><a href="https://i.sstatic.net/Wp7It.jpg" rel="noreferrer"><img src="https://i.sstatic.net/Wp7It.jpg" alt="Kimberley Australia" /></a></p>
<p><a href="https://i.sstatic.net/2k7dX.jpg" rel="noreferrer"><img src="https://i.sstatic.net/2k7dX.jpg" alt="enter image description here" /></a></p>
<p>There's also the countries of the Aegean Sea, which have a very Mediterranean climate.</p>
<p><a href="https://i.sstatic.net/fXHpJ.jpg" rel="noreferrer"><img src="https://i.sstatic.net/fXHpJ.jpg" alt="Aegean Sea" /></a></p>
<p>And there are also parts of the coasts of Myanmar, The Philippines, Indonesia and Fjordland in New Zealand which could be considered rugged.</p>
<p>To have a rugged coastline the coastline needs to be composed of rocky terrain, with valleys, gullies, canyons or mountains, that erodes slowly.</p>

CC BY-SA 4.0
2022-07-18T14:09:37.223Z
Fjordland in New Zealand has a colder climate.
gerrit
CC BY-SA 4.0
2022-07-18T17:39:16.313Z
Kauai and Molokai in Hawaii also have some of the largest sea cliffs in the world.
Kevin Carlson
CC BY-SA 4.0
2022-07-18T17:49:32.853Z
@gerrit: [Wikipedia](https://en.wikipedia.org/wiki/Fiordland#Ecology) states "Fiordland temperate forests". The latitude of Fjordland is 45 S. Two sources from NZ [1](http://fiordlandnationalpark.nz/climate/) & [2](https://www.doc.govt.nz/parks-and-recreation/places-to-go/fiordland/places/fiordland-national-park/know-before-you-go/weather-and-climate-in-fiordland/0) state summer temps of 17-22 C & 10-18 C with winter temps of 10-14 C and 1-9 C. Granted, its not tropical or Mediterranean & winter can be cold, but summer isn't.
Fred
CC BY-SA 4.0
2022-07-19T06:00:34.253Z
What matters is not the climate now, it's the climate when Fjordland was formed, i.e., was it glaciated or not.
Jean-Marie Prival
CC BY-SA 4.0
2022-07-19T09:08:29.057Z
You have a few counter examples, but when you zoom out a bit, it is noticeable that in the majority - colder areas appear more rugged than the warmer. Look at the west coast of America - Alaska, Canada and south Chile are rugged while it's relatively smooth from mainland USA down to the middle of Chile. North West Europe is rugged while from Spain down through Africa the coast is relatively smooth. There doesn't seem to so much jagged terrain in the warmer areas.
komodosp
CC BY-SA 4.0
2022-07-18T12:18:43.140Z
2022-07-18T16:08:05.140Z
2022-07-18T16:08:05.140Z
Fred
<p>As Fred's answer and some comments wrote, this is of course not so generally true.</p>
<p>What <em>is</em> true is that many rough coasts were formed by past glaciation. Obviously you don't tend to get many glaciers near sea level in tropical regions, so that's part of the answer!</p>
<p>But it's not only about temperature. A more precise statement is: <strong>Cold, humid winters cause rough coastlines</strong>. Why? because the rapid accumulation of snow and then ice causes thick glaciers that flow relatively fast, even without much initial elevation. And flowing glaciers are mighty roughness-shapers, both by eroding high ground and carving out fjords, as well as piling up moraines. Scandinavia is a prime example: lots of humid atlantic air snows down over Norway, where the glaciers have carved out all those fjords. In the past they also reached over Sweden, where the coast is by no means mountainous but nevertheless quite rough, because the leftover moraines funneled more recent water erosion into irregular shapes.</p>
<p>By contrast, cold climates with less snowfall (e.g. Antarctica) rather glaciate slowly in flat sheets that steadily drift into the sea, and don't cause the above features as much.</p>
<p>And of course rough coasts can also be formed my mechanisms unrelated to glaciation, such as volcanism and particular kinds of stratigraphy, which may be found in warm climates.</p>

CC BY-SA 4.0
2022-07-20T23:23:37.403Z
Can you say that freeze thaw has some influence on the rate of erosion?
D Duck
CC BY-SA 4.0
2022-07-21T08:08:20.620Z
@DDuck I thought about this. Frost weathering is no doubt a significant part of erosion in some climates, but this should rather _counteract_ the roughness-shaping effects, by systematically eroding exposed rock. On the other hand, glacial flow and erosion is probably also accelerated by partial thawing during summer.
leftaroundabout
CC BY-SA 4.0
2022-07-21T08:19:08.943Z
an interesting point that sounds plausible both ways
D Duck
CC BY-SA 4.0
2022-07-21T08:31:42.027Z
This open access paper might be of interest Fractal properties of shoreline changes on a storm-exposed island https://www.nature.com/articles/s41598-017-08924-9
D Duck
CC BY-SA 4.0
2022-07-19T16:47:51.197Z
2022-07-19T16:55:58.767Z
2022-07-19T16:55:58.767Z
leftaroundabout
<p>I've been playing <a href="https://worldle.teuteuf.fr/" rel="noreferrer">Worldle</a> for a while, and noticed that colder countries seem to have more rugged coasts. See Svalbard for example:</p>
<img src="https://i.sstatic.net/kyx1n.png" width="300">
<p>And Patagonia:</p>
<img src="https://i.sstatic.net/I9z0x.jpg" width="300">
<p>Whereas e.g. Bali is smoother:</p>
<img src="https://i.sstatic.net/kwKYz.jpg" width="300">
<p>Does it have something to do with the ocean being stronger in colder climates and washing away more of the &quot;softer&quot; parts of the coast over time? That's just a layman's guess, I'm really not sure.</p>
<p>Excited to learn about this if anyone knows the answer!</p>

CC BY-SA 4.0
2022-07-18T09:36:24.677Z
Please have a look at the French Western Coast, or at the North Sea Coast, or at the Hudson Bay. "Smooth" shores, in rather harsh climates. Also check out Baya California, or Greece, or the Philippines. "Rough" shores in (sub-)tropical climates. Next step: Compare geology & elevation.
Erik
CC BY-SA 4.0
2022-07-18T11:41:23.147Z
Ice -> fjords -> rugged coastline. See this related question: https://earthscience.stackexchange.com/q/23964/18081
Jean-Marie Prival
CC BY-SA 4.0
2022-07-18T21:34:19.813Z
Most obviously, might it be that in warmer climbs the shore has been battered only by water and in those colder zones, by ice?

Even when only water is battering the shore, the main tidal influence of the moon changes as we move further from the equator, as does the temperature difference between land and water.

Quite possibly irrelevant in human generations, but coastlines are formed over millennia.
Robbie Goodwin
CC BY-SA 4.0
2022-07-19T09:12:47.663Z
Is it that glaciers at some point in history are more likely in colder areas?
komodosp
<climate><coastal>
Why do colder climates have more rugged coasts?
Simon Bohnen
# Why do colder climates have more rugged coasts?

(Asked by: username_0 on 2022-07-18)

I've been playing [Worldle](https://worldle.teuteuf.fr/) for a while, and noticed that colder countries seem to have more rugged coasts. See Svalbard for example:

![](https://i.sstatic.net/kyx1n.png)

And Patagonia:

![](https://i.sstatic.net/I9z0x.jpg)

Whereas e.g. Bali is smoother:

![](https://i.sstatic.net/kwKYz.jpg)

Does it have something to do with the ocean being stronger in colder climates and washing away more of the "softer" parts of the coast over time? That's just a layman's guess, I'm really not sure.

Excited to learn about this if anyone knows the answer!

**Tags:** climate, coastal

> **Comments:**
> **username_1**: Please have a look at the French Western Coast, or at the North Sea Coast, or at the Hudson Bay. "Smooth" shores, in rather harsh climates. Also check out Baya California, or Greece, or the Philippines. "Rough" shores in (sub-)tropical climates. Next step: Compare geology & elevation.  
> **username_2**: Ice -> fjords -> rugged coastline. See this related question: https://earthscience.stackexchange.com/q/23964/18081  
> **username_3**: Most obviously, might it be that in warmer climbs the shore has been battered only by water and in those colder zones, by ice?  Even when only water is battering the shore, the main tidal influence of the moon changes as we move further from the equator, as does the temperature difference between land and water.  Quite possibly irrelevant in human generations, but coastlines are formed over millennia.  
> **username_4**: Is it that glaciers at some point in history are more likely in colder areas?  

---

## 2 answers

### Answer by username_8 on 2022-07-19. Score: 23 | Accepted answer

As username_5's answer and some comments wrote, this is of course not so generally true.

What *is* true is that many rough coasts were formed by past glaciation. Obviously you don't tend to get many glaciers near sea level in tropical regions, so that's part of the answer!

But it's not only about temperature. A more precise statement is: **Cold, humid winters cause rough coastlines**. Why? because the rapid accumulation of snow and then ice causes thick glaciers that flow relatively fast, even without much initial elevation. And flowing glaciers are mighty roughness-shapers, both by eroding high ground and carving out fjords, as well as piling up moraines. Scandinavia is a prime example: lots of humid atlantic air snows down over Norway, where the glaciers have carved out all those fjords. In the past they also reached over Sweden, where the coast is by no means mountainous but nevertheless quite rough, because the leftover moraines funneled more recent water erosion into irregular shapes.

By contrast, cold climates with less snowfall (e.g. Antarctica) rather glaciate slowly in flat sheets that steadily drift into the sea, and don't cause the above features as much.

And of course rough coasts can also be formed my mechanisms unrelated to glaciation, such as volcanism and particular kinds of stratigraphy, which may be found in warm climates.

> **Comments:**
> **username_9**: Can you say that freeze thaw has some influence on the rate of erosion?  
> **username_8**: @username_9 I thought about this. Frost weathering is no doubt a significant part of erosion in some climates, but this should rather _counteract_ the roughness-shaping effects, by systematically eroding exposed rock. On the other hand, glacial flow and erosion is probably also accelerated by partial thawing during summer.  
> **username_9**: an interesting point that sounds plausible both ways  
> **username_9**: This open access paper might be of interest Fractal properties of shoreline changes on a storm-exposed island https://www.nature.com/articles/s41598-017-08924-9  

---

### Answer by username_5 on 2022-07-18. Score: 23

Have you had a look at the northern coast of Russia or Alaska, in the cold Arctic? Having just looked at them on Google Earth, they are lengthy and seem very "un-rugged".

The northern coast of Russia:

[![Russia](https://i.sstatic.net/tRKxq.jpg)](https://i.sstatic.net/tRKxq.jpg)

The northern coast of Alaska:

[![Alaska](https://i.sstatic.net/d6zOH.jpg)](https://i.sstatic.net/d6zOH.jpg)

Opposite of that, in the hot subtropical Australia, the Kimberley coast in the north western part of the continent looks rugged:

[![Kimberley Australia](https://i.sstatic.net/Wp7It.jpg)](https://i.sstatic.net/Wp7It.jpg)

[![enter image description here](https://i.sstatic.net/2k7dX.jpg)](https://i.sstatic.net/2k7dX.jpg)

There's also the countries of the Aegean Sea, which have a very Mediterranean climate.

[![Aegean Sea](https://i.sstatic.net/fXHpJ.jpg)](https://i.sstatic.net/fXHpJ.jpg)

And there are also parts of the coasts of Myanmar, The Philippines, Indonesia and Fjordland in New Zealand which could be considered rugged.

To have a rugged coastline the coastline needs to be composed of rocky terrain, with valleys, gullies, canyons or mountains, that erodes slowly.

> **Comments:**
> **username_6**: Fjordland in New Zealand has a colder climate.  
> **username_7**: Kauai and Molokai in Hawaii also have some of the largest sea cliffs in the world.  
> **username_5**: @username_6: [Wikipedia](https://en.wikipedia.org/wiki/Fiordland#Ecology) states "Fiordland temperate forests". The latitude of Fjordland is 45 S. Two sources from NZ [1](http://fiordlandnationalpark.nz/climate/) & [2](https://www.doc.govt.nz/parks-and-recreation/places-to-go/fiordland/places/fiordland-national-park/know-before-you-go/weather-and-climate-in-fiordland/0) state summer temps of 17-22 C & 10-18 C with winter temps of 10-14 C and 1-9 C. Granted, its not tropical or Mediterranean & winter can be cold, but summer isn't.  
> **username_2**: What matters is not the climate now, it's the climate when Fjordland was formed, i.e., was it glaciated or not.  
> **username_4**: You have a few counter examples, but when you zoom out a bit, it is noticeable that in the majority - colder areas appear more rugged than the warmer. Look at the west coast of America - Alaska, Canada and south Chile are rugged while it's relatively smooth from mainland USA down to the middle of Chile. North West Europe is rugged while from Spain down through Africa the coast is relatively smooth. There doesn't seem to so much jagged terrain in the warmer areas.  

---

