<p>The effects of Earth's past climate variations on the landscape, especially <a href="https://en.wikipedia.org/wiki/Ice_age" rel="nofollow noreferrer">glaciation</a>, cannot be underestimated.</p>
<p>The multiple glacial advances and retreats over the last 4 million years or so have been a major (and sometimes the principal) force that shaped the current landscape. We're actually living in one of the temporary glacial minima - there will be more advances and retreats in the future.</p>
<p>Some important effects include:</p>
<ul>
<li><p>mass removal and depostion of rock material (it's why the US has good soil that used to be in Canada). Also, some sizeable landmasses such as <a href="https://en.wikipedia.org/wiki/Long_Island" rel="nofollow noreferrer">Long Island</a> consist of <a href="https://en.wikipedia.org/wiki/Moraine" rel="nofollow noreferrer">moraine</a>.</p>
</li>
<li><p>major gouges in the landscape, such as the ones that hold the Great Lakes, or <a href="https://en.wikipedia.org/wiki/U-shaped_valley" rel="nofollow noreferrer">U-shaped valley</a>s in the mountains</p>
</li>
<li><p><a href="https://en.wikipedia.org/wiki/Post-glacial_rebound" rel="nofollow noreferrer">isostatic rebound</a> affecting coasts to this day</p>
</li>
<li><p><a href="https://en.wikipedia.org/wiki/Estuary" rel="nofollow noreferrer">estuaries</a> (drowned river valleys) and <a href="https://en.wikipedia.org/wiki/Barrier_island" rel="nofollow noreferrer">barrier island</a>s that result from sea level drop during a glacial maximum, followed by sea level rise as they melt. The <a href="https://en.wikipedia.org/wiki/Black_Sea" rel="nofollow noreferrer">Black Sea</a> is a drowned freshwater lake.</p>
</li>
<li><p>ancient <a href="https://en.wikipedia.org/wiki/Glacial_lake" rel="nofollow noreferrer">glacial lake</a>s <a href="https://en.wikipedia.org/wiki/Lake_Agassiz" rel="nofollow noreferrer">created by trapped meltwater</a> or <a href="https://en.wikipedia.org/wiki/Pluvial_lake" rel="nofollow noreferrer">increased rainfall</a>, leaving <a href="https://en.wikipedia.org/wiki/Varve" rel="nofollow noreferrer">lake bottom sediment</a> in the soil and fossil shorelines. Sometimes the lakes drained catastrophically, leaving weird erosional features such as the <a href="https://en.wikipedia.org/wiki/Channeled_Scablands" rel="nofollow noreferrer">Channeled Scablands</a>. Sometimes they never drained at all (the Great Lakes).</p>
</li>
<li><p>aeolian (<a href="https://en.wikipedia.org/wiki/Loess" rel="nofollow noreferrer">loess</a>) deposits from dessicated areas near the ice front</p>
</li>
</ul>
<p>And that's just what I could think of in 5 minutes.</p>
<p>Not only that, major glaciations in the distant past have affected the geological record, such as the <a href="https://en.wikipedia.org/wiki/Snowball_Earth" rel="nofollow noreferrer">Snowball Earth</a> episodes ~ 700 Ma ago that nearly eradicated a billion years of stratigraphy.</p>

CC BY-SA 4.0
2021-07-15T14:27:29.833Z
I remember a field trip ~45 years ago where the teacher pointed to large boulders and explained that they were pushed there by glaciers. Geologists could tell this because their composition was unlike the local bedrock.
Barmar
CC BY-SA 4.0
2021-07-15T14:46:37.947Z
@barmar Those are called "[glacial erratics](https://en.wikipedia.org/wiki/Glacial_erratic)".
Spencer
CC BY-SA 4.0
2021-07-15T19:54:37.057Z
Related, and links into the human impact, but perhaps not appropriate for schools: http://www.deepseanews.com/2012/06/how-presidential-elections-are-impacted-by-a-100-million-year-old-coastline/
Tim
CC BY-SA 4.0
2021-07-16T19:28:47.253Z
As anyone who's tried growing anything in glacial materials will tell you: they're the worst, though not as bad as playground sand. That "good" midwestern soil is a direct result of Pleistocene herbivore droppings when the average size animal size was 200+lbs.
Knob Scratcher
CC BY-SA 4.0
2021-07-16T20:14:38.397Z
@KnobScratcher Perhaps, but till can grow grass for those herbivores to graze in; otherwise they wouldn't have been there to poop in..
Spencer
CC BY-SA 4.0
2021-07-14T21:53:40.567Z
2021-07-17T23:15:04.947Z
2021-07-17T23:15:04.947Z
Spencer
<p>You could mention the fact that the solid Earth (i.e., not the atmosphere) is slowly cooling down, as the two main sources of heat, primordial and radioactive, are slowly decaying. Because of this, the planet may become tectonically dead at some point.</p>
<p>Gradual change over long periods of time is known as <a href="https://en.wikipedia.org/wiki/Uniformitarianism" rel="nofollow noreferrer">uniformitarianism</a>, and has been opposed to catastrophism in the 19th century. From a history of sciences point of view, it could be worth mentioning the dispute between the two theories (and the fact that the evolution of Earth is actually driven by a bit of both).</p>

CC BY-SA 4.0
2021-07-17T00:21:59.023Z
Assuming that the Earth is not hit by another Thea-level asteroid strike.
chiggsy
CC BY-SA 4.0
2021-07-15T07:37:37.110Z
2021-07-15T11:53:26.970Z
2021-07-15T11:53:26.970Z
Jean-Marie Prival
<p>Major geologic changes occur during natural events.  Events like wildfire, floods, earthquakes, drought, volcanic eruptions, tsunamis, etc. can severely alter the landscape and allow new geologic processes to take place.  For instance, after a landscape is hit by wildfire, it is easily subject to flash flooding and you get soil loss.  This was not really &quot;slow&quot; on a geologic time scale, it was circumstantial.</p>
<p>This biggest event of all is a meteor impact, which can cause tsunamis, fires, etc. and also introduce new material to Earth.</p>
<p>Perhaps overlooked on your list is the affect that life has on geology:
from microorganisms and worms in the soil creating humus to <a href="https://www.tandfonline.com/doi/abs/10.1080/15230430.1999.12003328#:%7E:text=Animals%20can%20exert%20a%20very,sediment%20transport%20in%20the%20alpine.&amp;text=Animals%20exert%20a%20direct%20influence,needle%20ice%2C%20and%20wind%20erosion." rel="nofollow noreferrer">larger animals</a> that burrow and dig, to vegetation that can transform local soil, moisture, and temperature... plants and animals do make a difference.</p>
<p>Finally, I know you said you will talk about people's influence later, but make sure they know we are in a new geologic epoch, the <a href="https://en.wikipedia.org/wiki/Anthropocene" rel="nofollow noreferrer">anthropocene</a>.  And, while human influence on climate is very important, we are possibly causing a bigger geologic effect with plastic waste.</p>

CC BY-SA 4.0
2021-07-16T05:29:09.487Z
2021-07-16T05:29:09.487Z
f.thorpe
<ol>
<li><p><strong>Carbon cycling through the mantle</strong> is a hugely important geologic process. Carbon gets into the mantle when subducted continental arc materials bearing rich, organic runoff are carried to depth, then exuded through volcanism at plate boundaries. That rich organic runoff is created by rain which is deeply influenced by...</p>
</li>
<li><p><strong>Oceanic currents</strong> which largely control planet-wide weather. These currents are influenced by plate tectonics, Milankovich Cycles, as well as global temperature.</p>
</li>
</ol>
<p>Technically, #2 is an &quot;oceanographic&quot; process, but it's influence on crustal geologic processes is profound. Processes like the flipping of the poles, the distancing moon, wind erosion are interesting but play little part influencing the bigger geological picture.</p>
<p>Your later lesson might include how human-caused global warming is affecting global ocean currents and disturbing stable processes reflected in the geochemistry at plate boundaries. You might tell your kids how 25 million years from now, a terrestrial-squid geology grad student may study the relationship between the sudden disappearance of carbon-rich andesites from the western South American plate and the anthropocene.</p>
<p>Incidentally, if you'd like to show your students some riveting &quot;future-geology&quot;, I highly recommend the series &quot;<a href="https://www.thefutureiswild.com/" rel="nofollow noreferrer">The Future is Wild</a>&quot;, in which global geology (and evolution) is observed 5, 100, and 200 million years into the future.</p>

CC BY-SA 4.0
2021-07-16T20:08:49.490Z
2021-07-16T20:08:49.490Z
Knob Scratcher
<p>I am teaching a secondary school course on my state's local history. The textbook begins with the history of the first humans, yet I think it is unfair not to start back much earlier, introducing the geologic history.</p>
<p>Students finished a lesson on the slow changes that took place over the past 4.5 billion years on Earth, gradually leading to the formation of our state. I want the students to understand these changes haven't stopped, just we maybe can't see everything happening, as it happens slowly.</p>
<p>A later lesson will focus on human changes, but I want to first cover natural changes:</p>
<ul>
<li>Earth's magnetic pole is moving.</li>
<li>Moon slowly getting further away.</li>
<li>Days are slowly getting longer.</li>
<li>Tectonic plate slowly moving 1 inch west-southwest.</li>
<li>Wind and rain slowly shaping landscape.</li>
</ul>
<p>Without having a geology background, I'm quite concerned I overlooked some important changes. There are some locally specific features I identified (such as a slowly-splitting rift valley), but are there any other major changes I ought to include?</p>

CC BY-SA 4.0
2021-07-15T11:11:58.537Z
Not directly geology, but related to history before the first humans: changing composition of the atmosphere, [apparition (and extinction) of various forms of life](https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_history_of_life), including mass [extinction events](https://en.wikipedia.org/wiki/List_of_extinction_events), with their multiple causes (mostly volcanism, but also meteor strikes and more...).
jcaron
CC BY-SA 4.0
2021-07-16T05:00:32.383Z
I heavily changed the title to make it simpler and clear.  Hopefully I captured the intent.
f.thorpe
CC BY-SA 4.0
2021-07-16T11:40:16.730Z
People may have more specific ideas if you mention which state you are in.
jcaron
CC BY-SA 4.0
2021-07-16T14:28:04.157Z
@f.thorpe thank you
Village
CC BY-SA 4.0
2021-07-16T14:29:02.663Z
@jcaron in the US Southwest, but was sure there are general answers that apply everywhere
Village
CC BY-SA 4.0
2021-07-16T14:40:26.797Z
For a state-oriented explication of past and present geology, have a look at the [Roadside Geology](https://mountain-press.com/collections/roadside-geology) series of books. I have quite a collection, and enjoy them immensely.
John P Doty
CC BY-SA 4.0
2021-07-16T15:10:48.107Z
Note: There was a title edit that changed the scope of this question a little.
Spencer
CC BY-SA 4.0
2021-07-16T21:26:35.883Z
Grand Canyon is probably continuing to get deeper, Rockies probably getting higher, San Andreas fault continuing to move…
jcaron
CC BY-SA 4.0
2021-07-17T12:27:35.513Z
@JohnPDoty I will look into that for state-specific answers, but for purposes of this question, looking to things that apply pretty much everywhere.
Village
<geology><earth-history>
What significant factors influencing geological change are still occurring?
Village
# What significant factors influencing geological change are still occurring?

(Asked by: username_0 on 2021-07-14)

I am teaching a secondary school course on my state's local history. The textbook begins with the history of the first humans, yet I think it is unfair not to start back much earlier, introducing the geologic history.

Students finished a lesson on the slow changes that took place over the past 4.5 billion years on Earth, gradually leading to the formation of our state. I want the students to understand these changes haven't stopped, just we maybe can't see everything happening, as it happens slowly.

A later lesson will focus on human changes, but I want to first cover natural changes:

* Earth's magnetic pole is moving.
* Moon slowly getting further away.
* Days are slowly getting longer.
* Tectonic plate slowly moving 1 inch west-southwest.
* Wind and rain slowly shaping landscape.

Without having a geology background, I'm quite concerned I overlooked some important changes. There are some locally specific features I identified (such as a slowly-splitting rift valley), but are there any other major changes I ought to include?

**Tags:** geology, earth-history

> **Comments:**
> **username_1**: Not directly geology, but related to history before the first humans: changing composition of the atmosphere, [apparition (and extinction) of various forms of life](https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_history_of_life), including mass [extinction events](https://en.wikipedia.org/wiki/List_of_extinction_events), with their multiple causes (mostly volcanism, but also meteor strikes and more...).  
> **username_2**: I heavily changed the title to make it simpler and clear.  Hopefully I captured the intent.  
> **username_1**: People may have more specific ideas if you mention which state you are in.  
> **username_0**: @username_2 thank you  
> **username_0**: @username_1 in the US Southwest, but was sure there are general answers that apply everywhere  
> **username_3**: For a state-oriented explication of past and present geology, have a look at the [Roadside Geology](https://mountain-press.com/collections/roadside-geology) series of books. I have quite a collection, and enjoy them immensely.  
> **username_4**: Note: There was a title edit that changed the scope of this question a little.  
> **username_1**: Grand Canyon is probably continuing to get deeper, Rockies probably getting higher, San Andreas fault continuing to move…  
> **username_0**: @username_3 I will look into that for state-specific answers, but for purposes of this question, looking to things that apply pretty much everywhere.  

---

## 4 answers

### Answer by username_4 on 2021-07-14. Score: 15

The effects of Earth's past climate variations on the landscape, especially [glaciation](https://en.wikipedia.org/wiki/Ice_age), cannot be underestimated.

The multiple glacial advances and retreats over the last 4 million years or so have been a major (and sometimes the principal) force that shaped the current landscape. We're actually living in one of the temporary glacial minima - there will be more advances and retreats in the future.

Some important effects include:

* mass removal and depostion of rock material (it's why the US has good soil that used to be in Canada). Also, some sizeable landmasses such as [Long Island](https://en.wikipedia.org/wiki/Long_Island) consist of [moraine](https://en.wikipedia.org/wiki/Moraine).
* major gouges in the landscape, such as the ones that hold the Great Lakes, or [U-shaped valley](https://en.wikipedia.org/wiki/U-shaped_valley)s in the mountains
* [isostatic rebound](https://en.wikipedia.org/wiki/Post-glacial_rebound) affecting coasts to this day
* [estuaries](https://en.wikipedia.org/wiki/Estuary) (drowned river valleys) and [barrier island](https://en.wikipedia.org/wiki/Barrier_island)s that result from sea level drop during a glacial maximum, followed by sea level rise as they melt. The [Black Sea](https://en.wikipedia.org/wiki/Black_Sea) is a drowned freshwater lake.
* ancient [glacial lake](https://en.wikipedia.org/wiki/Glacial_lake)s [created by trapped meltwater](https://en.wikipedia.org/wiki/Lake_Agassiz) or [increased rainfall](https://en.wikipedia.org/wiki/Pluvial_lake), leaving [lake bottom sediment](https://en.wikipedia.org/wiki/Varve) in the soil and fossil shorelines. Sometimes the lakes drained catastrophically, leaving weird erosional features such as the [Channeled Scablands](https://en.wikipedia.org/wiki/Channeled_Scablands). Sometimes they never drained at all (the Great Lakes).
* aeolian ([loess](https://en.wikipedia.org/wiki/Loess)) deposits from dessicated areas near the ice front

And that's just what I could think of in 5 minutes.

Not only that, major glaciations in the distant past have affected the geological record, such as the [Snowball Earth](https://en.wikipedia.org/wiki/Snowball_Earth) episodes ~ 700 Ma ago that nearly eradicated a billion years of stratigraphy.

> **Comments:**
> **username_5**: I remember a field trip ~45 years ago where the teacher pointed to large boulders and explained that they were pushed there by glaciers. Geologists could tell this because their composition was unlike the local bedrock.  
> **username_4**: @username_5 Those are called "[glacial erratics](https://en.wikipedia.org/wiki/Glacial_erratic)".  
> **username_6**: Related, and links into the human impact, but perhaps not appropriate for schools: http://www.deepseanews.com/2012/06/how-presidential-elections-are-impacted-by-a-100-million-year-old-coastline/  
> **username_7**: As anyone who's tried growing anything in glacial materials will tell you: they're the worst, though not as bad as playground sand. That "good" midwestern soil is a direct result of Pleistocene herbivore droppings when the average size animal size was 200+lbs.  
> **username_4**: @username_7 Perhaps, but till can grow grass for those herbivores to graze in; otherwise they wouldn't have been there to poop in..  

---

### Answer by username_8 on 2021-07-15. Score: 4

You could mention the fact that the solid Earth (i.e., not the atmosphere) is slowly cooling down, as the two main sources of heat, primordial and radioactive, are slowly decaying. Because of this, the planet may become tectonically dead at some point.

Gradual change over long periods of time is known as [uniformitarianism](https://en.wikipedia.org/wiki/Uniformitarianism), and has been opposed to catastrophism in the 19th century. From a history of sciences point of view, it could be worth mentioning the dispute between the two theories (and the fact that the evolution of Earth is actually driven by a bit of both).

> **Comments:**
> **username_9**: Assuming that the Earth is not hit by another Thea-level asteroid strike.  

---

### Answer by username_2 on 2021-07-16. Score: 1

Major geologic changes occur during natural events. Events like wildfire, floods, earthquakes, drought, volcanic eruptions, tsunamis, etc. can severely alter the landscape and allow new geologic processes to take place. For instance, after a landscape is hit by wildfire, it is easily subject to flash flooding and you get soil loss. This was not really "slow" on a geologic time scale, it was circumstantial.

This biggest event of all is a meteor impact, which can cause tsunamis, fires, etc. and also introduce new material to Earth.

Perhaps overlooked on your list is the affect that life has on geology:
from microorganisms and worms in the soil creating humus to [larger animals](https://www.tandfonline.com/doi/abs/10.1080/15230430.1999.12003328#:%7E:text=Animals%20can%20exert%20a%20very,sediment%20transport%20in%20the%20alpine.&text=Animals%20exert%20a%20direct%20influence,needle%20ice%2C%20and%20wind%20erosion.) that burrow and dig, to vegetation that can transform local soil, moisture, and temperature... plants and animals do make a difference.

Finally, I know you said you will talk about people's influence later, but make sure they know we are in a new geologic epoch, the [anthropocene](https://en.wikipedia.org/wiki/Anthropocene). And, while human influence on climate is very important, we are possibly causing a bigger geologic effect with plastic waste.


---

### Answer by username_7 on 2021-07-16. Score: 1

1. **Carbon cycling through the mantle** is a hugely important geologic process. Carbon gets into the mantle when subducted continental arc materials bearing rich, organic runoff are carried to depth, then exuded through volcanism at plate boundaries. That rich organic runoff is created by rain which is deeply influenced by...
2. **Oceanic currents** which largely control planet-wide weather. These currents are influenced by plate tectonics, Milankovich Cycles, as well as global temperature.

Technically, #2 is an "oceanographic" process, but it's influence on crustal geologic processes is profound. Processes like the flipping of the poles, the distancing moon, wind erosion are interesting but play little part influencing the bigger geological picture.

Your later lesson might include how human-caused global warming is affecting global ocean currents and disturbing stable processes reflected in the geochemistry at plate boundaries. You might tell your kids how 25 million years from now, a terrestrial-squid geology grad student may study the relationship between the sudden disappearance of carbon-rich andesites from the western South American plate and the anthropocene.

Incidentally, if you'd like to show your students some riveting "future-geology", I highly recommend the series "[The Future is Wild](https://www.thefutureiswild.com/)", in which global geology (and evolution) is observed 5, 100, and 200 million years into the future.


---

