I recently went for a hike up a gorge and then down a ravine. What is the difference between a gorge and a ravine? And how does canyon fit in?
My impression was that there was an implied scale, where a ravine is smaller than a gorge, which is smaller than a canyon.
All of these geographical features seem to be created in the same way: a river or stream eroding hard rocky material, giving steep sides.
Looking at Wikipedia, there are entries for both "ravine" and "canyon". "Gorge" redirects to "canyon". It seems to imply that all three words can be used interchangeably. But are there some technical differences between these words to inform their usage?
Edit: adding definitions
Oxford Living English dictionary definitions: (edit: thanks Mitch)
gorge: A narrow valley between hills or mountains, typically with steep rocky walls and a stream running through it.
ravine: A deep, narrow gorge with steep sides.
canyon: A deep gorge, typically one with a river flowing through it, as found in North America.
gully: (1) A ravine formed by the action of water; or (2) A deep artificial channel serving as a gutter or drain.
Cambridge English dictionary:
gorge: a deep, narrow valley with steep sides, usually formed by a river or stream cutting through hard rock
ravine: a deep narrow valley with steep sides
canyon: a large valley with very steep sides and usually a river flowing along the bottom
gully: (1) a narrow valley or channel with steep sides, made by a fast-flowing stream; or (2) an artificial channel that is used to get rid of water that is not wanted
Merriam-Webster English dictionary:
gorge: a narrow passage through land especially: a narrow steep-walled canyon or part of a canyon
ravine: a small narrow steep-sided valley that is larger than a gully and smaller than a canyon and that is usually worn by running water
canyon: a deep narrow valley with steep sides and often with a stream flowing through it
gully: (1) a trench which was originally worn in the earth by running water and through which water often runs after rains; or (2) a small valley or gulch
The definition of canyon from Cambridge seems to fit the best, considering the large size of the Grand Canyon, or Fish River Canyon. Merriam-Webster seems to agree that a ravine is smaller than a canyon, and also seems to define gorge as a smaller canyon. Overall, given these definitions, I would use canyon for the largest land-forms, and gully for the smallest ones. Gorge and ravine seem like they could be used interchangeably.
Best Answer
Words aren't computer programs. They aren't exactly specified. There's a lot of room for slight differences. Pebble, stone, rock. Honesty, integrity, fidelity. Kingly, royal, regal.
There are no exact synonyms, but you can often replace one word for another and get by.
Definitions of words are not the words themselves. They are attempts at capturing how to use words, but you can't, as you can in math, replace a word with its definition and have everything work out as intended.
Lexicographers are highly knowledgeable about the nuances of words, but they are constrained by page space (or nowadays by reader attention) to limit the number of words in a definition.
Also, 'canyon' is a borrowing from Spanish into English and is common in the southwest US (like 'arroyo').
All that said, I share your vague perception that a canyon is bigger than a gorge which is bigger than a ravine (which is bigger than a gulley). I feel like a river goes through a canyon, a small river or stream through a gorge, a creek or brook through a ravine, and a gulley is often barely a stream to dry.
All that said, each of these words may have very specific technical definitions for use by geo-morphologists, possibly involving wall steepness/height/complexity (smooth vs jagged), volume of water, length, surrounding geology, etc. This may lead to things being called one thing in a gazette but called by scientists one of the others. (i.e. the Three Gorges on the Yangtze may be considered a canyon technically).
There are online glossaries or geomorphology. One gives
It gives for your desired terms the following:
Gorge A steep-sided, narrow floored valley cut into bedrock
Ravine - strangely, not defined but used multiple times for versions of ravine
Canyon A deeply incised, steep-sided river valley
Gully A small hollow or channel incised into sediments or unconsolidated rock by running water
For a very specified definition:
There are all sorts of words for different scales and topologies of watershed areas: gulch, hollow, couloir, valley, coombe (or cwm for word-nerds) and on and on.
Note that these technical definitions are not as interreferenced as the informal definitions given by the dictionaries. I find the dictionary definitions you found to be somewhat unsatisfactory in comparison because of them each referring to the other.