<p>It's an interesting question, but in practice I think it's impossible to answer. It's very difficult to measure the rates of many of those processes, and the divisions between rock types can be quite ill-defined (for example, in <a href="http://en.wikipedia.org/wiki/Migmatite">migmatites</a>). There's no scientific instrument we can point at a chunk of the earth which will tell us "in this region, 29.4 megatons of sedimentary rock became metamorphic rock during the past year".</p>

<p>What we can say, at least, is that the global balance of these processes is not constant over time. For example, during the <a href="http://en.wikipedia.org/wiki/Deccan_Traps">Deccan Traps</a> eruptions there was an increase in the rate of formation of igneous rock through solidification of magma.</p>

<p>The classic rock cycle diagram you posted probably encourages this kind of question, because it makes it look like a neat, closed system with well-defined boundaries and comparable quantities of each rock type. It's a very useful simplification for many purposes, but remember that these processes are occurring at or near the earth's surface. This whole system sits on top of the mantle (which is vast compared to the volume of crustal rock), and material is continually being passed between the two, so it's far from being a closed system.</p>

CC BY-SA 3.0
2018-01-23T21:17:41.927Z
How relatively important would events like the uplift of the Himalayas be (increasing erosion)?
Keith McClary
CC BY-SA 3.0
2014-11-15T09:34:02.617Z
+1 Excellent answer.
Gimelist
CC BY-SA 3.0
2014-05-05T07:31:15.507Z
2014-05-05T08:10:07.137Z
2014-05-05T08:10:07.137Z
Pont
<ol>
<li><p>There is some studies pointing to a bigger activity of tectonism in Mid-Atlantic Ridges on ice ages. With more water freezed in south and north poles and less water in the ocean, the weight of water over South America plate(and others) are lower and the tectonics plates will be more active.</p></li>
<li><p>In low rain periods, less chemical intemperism will happen(main source of sediments).</p></li>
</ol>

<p>These factors and others more should modify the proportion of rock kinds.</p>

CC BY-SA 3.0
2015-02-26T06:45:55.807Z
2015-02-26T06:45:55.807Z
exg
<p>The standard representation of the rock cycle usually looks like this:</p>

<p><img src="https://i.sstatic.net/1qxMW.jpg" alt="enter image description here"></p>

<p>Does each stage of the rock cycle currently balance? That is, are the various processes in dynamic equilibrium, so that the proportions of the different rock types remain constant?</p>

<p>If the processes are not in equilibrium, which types of rock are currently increasing in overall prevalence, and which are decreasing?</p>

CC BY-SA 3.0
2014-05-05T05:31:45.300Z
I'm not really sure what this is asking. Are you asking which rock forming processes is dominate on Earth?
Neo
CC BY-SA 3.0
2014-05-05T07:39:51.903Z
@Neo I have rewritten the question to make it clearer (I hope I haven't misconstrued the asker's meaning in doing so). I've also attempted an answer. I don't think that this question can be answered directly, but I nevertheless think it's useful in clearing up some simplifications and misconceptions.
Pont
CC BY-SA 3.0
2014-05-05T10:10:06.257Z
@Pont Thank you so much. I don't know English well :( You really makes it clearer. Thank you once again.
Poomrokc The 3years
<geology><rocks><petrology><geodynamics>
Are the processes of the rock cycle currently in dynamic equilibrium?
Poomrokc The 3years
# Are the processes of the rock cycle currently in dynamic equilibrium?

(Asked by: username_0 on 2014-05-05)

The standard representation of the rock cycle usually looks like this:

![enter image description here](https://i.sstatic.net/1qxMW.jpg)

Does each stage of the rock cycle currently balance? That is, are the various processes in dynamic equilibrium, so that the proportions of the different rock types remain constant?

If the processes are not in equilibrium, which types of rock are currently increasing in overall prevalence, and which are decreasing?

**Tags:** geology, rocks, petrology, geodynamics

> **Comments:**
> **username_1**: I'm not really sure what this is asking. Are you asking which rock forming processes is dominate on Earth?  
> **username_2**: @username_1 I have rewritten the question to make it clearer (I hope I haven't misconstrued the asker's meaning in doing so). I've also attempted an answer. I don't think that this question can be answered directly, but I nevertheless think it's useful in clearing up some simplifications and misconceptions.  
> **username_0**: @username_2 Thank you so much. I don't know English well :( You really makes it clearer. Thank you once again.  

---

## 2 answers

### Answer by username_2 on 2014-05-05. Score: 18

It's an interesting question, but in practice I think it's impossible to answer. It's very difficult to measure the rates of many of those processes, and the divisions between rock types can be quite ill-defined (for example, in [migmatites](http://en.wikipedia.org/wiki/Migmatite)). There's no scientific instrument we can point at a chunk of the earth which will tell us "in this region, 29.4 megatons of sedimentary rock became metamorphic rock during the past year".

What we can say, at least, is that the global balance of these processes is not constant over time. For example, during the [Deccan Traps](http://en.wikipedia.org/wiki/Deccan_Traps) eruptions there was an increase in the rate of formation of igneous rock through solidification of magma.

The classic rock cycle diagram you posted probably encourages this kind of question, because it makes it look like a neat, closed system with well-defined boundaries and comparable quantities of each rock type. It's a very useful simplification for many purposes, but remember that these processes are occurring at or near the earth's surface. This whole system sits on top of the mantle (which is vast compared to the volume of crustal rock), and material is continually being passed between the two, so it's far from being a closed system.

> **Comments:**
> **username_4**: +1 Excellent answer.  
> **username_3**: How relatively important would events like the uplift of the Himalayas be (increasing erosion)?  

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### Answer by username_5 on 2015-02-26. Score: 3

1. There is some studies pointing to a bigger activity of tectonism in Mid-Atlantic Ridges on ice ages. With more water freezed in south and north poles and less water in the ocean, the weight of water over South America plate(and others) are lower and the tectonics plates will be more active.
2. In low rain periods, less chemical intemperism will happen(main source of sediments).

These factors and others more should modify the proportion of rock kinds.


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