All Questions

Filter by
Sorted by
Tagged with
7
votes
2answers
1k views

Life on Earth previous to us

I've seen in several places that there seems to be an extinction cycle on Earth of approximately 27 million years. I've read this here: http://www.dailymail.co.uk/sciencetech/article-1294372/Life-...
10
votes
1answer
255 views

Permeability of well screen as a limitation to a slug-in test

If you were to do a slug-in test where you put in a known volume of water, would there be a point where, say if the formation was extremely permeable, the permeability of the screen itself would be ...
21
votes
6answers
95k views

Is there a difference between rock and stone?

I couldn't find the definitions from either source: Geology Dictionary Glossary of Geologic Terms
11
votes
1answer
127 views

Estimate litter production

How would one go about estimating litter production (fine root turnover, leaves, etc.) for a forested area? I have some estimates from literature - which were derived from models, but I'd like to ...
10
votes
1answer
562 views

What's the geological period of the birth of the river Ganges?

Avatarana or Descent of the Ganges (extracted from Wikipedia): "In late May or early June every year, Hindus celebrate the avatarana or descent of the Ganges from heaven to earth." There are ...
13
votes
1answer
206 views

Is Mars' mantle homogeneous or heterogeneous and what might this say about mantle convection?

A supervisor of mine made an off-hand comment about the fact that Mars used to have plate tectonics, and there is evidence that Mars used to have plate tectonics, however now it does not. The theory ...
10
votes
1answer
3k views

What is a massif and what differentiates it from other types of mountains?

Wikipedia says that a massif is "a section of a planet's crust that is demarcated by faults or flexures." It goes on to list mountain-like objects. Is it not true that most mountains are created by ...
13
votes
3answers
628 views

Ozone gas (O₃) endurance in the atmosphere

If I release some ozone gas (O3) to the atmosphere, for how much time will it stay there in its original form? Does it change to some other form by reacting with other atmospheric constituents?
13
votes
1answer
303 views

What can I use as a heatproof, non-magnetic glue for samples?

I, and many of my palaeomagnetist colleagues, often use thermal demagnetization (potentially up to 800°C) in our studies. Usually a stepwise technique is employed, so each sample is heated -- often 20 ...
10
votes
1answer
4k views

What kind of minerals have no cleavage plane?

Why does quartz have no cleavage plane and halite does? What do I need to know about the specific mineral so that I can decide whether it has cleavage or not? I need some kind of rule.
11
votes
2answers
315 views

How do meteorologists grade their past forecasts?

In every professional field, practitioners may come home at the end of the day and say "Yeah! I knocked it out of the park!", or alternatively "Oh, man. Gotta do better tomorrow." What about ...
17
votes
1answer
5k views

What is the range of possible atmospheric pressures on the surface of the Earth?

I'm developing an Android app which uses a pressure sensor. Due to storage limitations I have to normalize and scale the atmospheric pressure values. For this I need to know the extreme values of ...
12
votes
2answers
561 views

How does radiogenic argon-40 get into the atmosphere?

There's an awful lot of argon in the atmosphere: about 0.93% of the atmosphere is argon[1], making it the third-most abundant gas after N2 and O2. As I understand it, most of it is produced by the ...
7
votes
1answer
319 views

Is it true that “[sand] grains in the Coconino Sandstone come from the Appalachian Mountains”?

The Creation Museum is a terrifying place for scientists of all stripes. One of their exhibits is the "Flood Geology" exhibit, which purports to explain how a flood of (literally) Biblical proportions ...
16
votes
2answers
7k views

How does the precession of the Earth's apses affect climate?

The gravitational influence of the gas giants (plus general-relativistic effects) are known to cause the apses of the Earth's orbit to precess. For an illustration of that process, see this image. Now,...
14
votes
1answer
122 views

In what sense did the Oklo reactor “trap” its own nuclear waste?

A number of popular writings on the natural fission reactor at Oklo, Gabon (e.g. here) state that some of the energetic byproducts (krypton and xenon, presumably 85Kr and 133Xe) of the reactor were "...
13
votes
1answer
149 views

Does the Great Pacific Garbage Patch increase sedimentation rates over the patch?

As in, does the debris in the patch area eventually sink? And if so, could sedimentation measurements over these regions provide a more fine-scaled measure of environmental conditions than ...
6
votes
2answers
14k views

Why are there no crystals with 5-fold symmetry?

They say you can't pack objects like pentagons or octagons such that they fill up space entirely and that that's one reason there is no 5-fold or 8-fold rotational axis. Are you telling me you can ...
3
votes
0answers
86 views

Is the number of high/low pressure regions different at low pressure levels at high pressure levels?

Is there a higher number of mid-latitude high/low pressure regions at 850 mb, as compared to the number of high/low pressure regions at 200 mb? And if so, why?
2
votes
0answers
99 views

What is the significance of the Vertical integral of northward kinetic energy flux?

This is a field in the ERA-Interim dataset. What is its significance, and what is it important for?
5
votes
1answer
536 views

Can thunderstorms be thought of as a heat engine?

Or in other words, can they be seen as sources of heat transport? If so, what can be thought of as the heat source, and what can be thought of as the heat sink?
6
votes
0answers
88 views

How much heat do hurricanes transport from equatorial to more polar latitudes, and from ocean to atmosphere?

And how much does this heat compare with the total fraction of heat otherwise transported from equatorial to polar latitudes, and from ocean to atmosphere?
8
votes
1answer
226 views

How does El Niño affect thunderstorm/tornado/CAPE activity in the central United States?

Or in other words, does it increase the amount of heat+moisture advection from the Gulf of Mexico into the Central United States? And is this increase associated with increased CAPE/tornado/...
6
votes
1answer
290 views

Was the Southern Hemisphere cooler during the Younger Dryas?

The Younger Dryas was associated with less heat transport from the Southern Hemisphere to the Northern Hemisphere (and a lower flux of the meridional overturning circulation). So I'm wondering - what ...
1
vote
1answer
583 views

How to perform precipitation data analysis? [closed]

I want to make precipitation data analysis for the Latvian territory. I only have meteorological stations and reanalysis data. My data from meteorological stations are in the format: ...
17
votes
2answers
367 views

What geophysical events can (temporarily) increase the Earth's rate of rotation?

My understanding is that the dominant factor behind the slowing of the Earth's rotation (i.e. the lengthening of the day) is tidal friction induced by the Moon's gravity. As seen on the graph below, ...
22
votes
2answers
344 views

What properties must a rocky body possess in order to exhibit plate tectonics?

The Earth exhibits plate tectonics, but the other terrestrial planets do not (though Mars and Venus may have exhibited plate tectonics in the past). What is "special" about Earth that allows it to ...
14
votes
1answer
626 views

How long does it take for the atmosphere to mix?

If I release a say, one litre of gas, at a particular point on the planet, how soon, on average, would it take to be distributed evenly (mixed) across the entire earth's atmosphere?
28
votes
1answer
2k views

What factors determine the number of Hadley cells for a planet?

We know (think?) that Earth has three Hadley cells per hemisphere, but from observing gas giants such as Jupiter, we see that they have many more cells. According to a link from a comment in this ...
11
votes
1answer
274 views

Regarding the theory of the origin of water on Earth through meteorites, why wouldn't the water evaporate on impact?

Water on earth has been theorized to have come through comets trapped inside crystals. But why wouldn't that water evaporate on impact, and wouldn't the atmosphere at that time allow the vapours to ...
18
votes
2answers
1k views

Historically, how has the fraction of Earth covered by water changed?

Today, 70.8% of the Earth is covered in water (± a few tenths of a percent depending on how you account for lakes).1 How has this figure changed over the history of the Earth, and why? Of course, if ...
12
votes
1answer
591 views

What causes “shallow” moonquakes?

It is thought that "deep" moonquakes are caused by tidal forces exerted on the Moon by the Earth and Sun. Some other sorts of moonquakes are thought to be caused by impacts, or by thermal expansion (...
5
votes
1answer
108 views

Why is the eastern Pacific full of stratocumulus clouds, and why do they have so much variation in net radiation?

They can be seen in the diagram below (of the CERES radiation dataset - supposedly they contribute a lot to the total variance in net radiation, which is the sum of SW and LW) - just west of Peru and ...
6
votes
2answers
1k views

How will climate change affect the latitudinal distribution of precipitation over each latitudinal region?

In other words... How will it affect precipitation in the tropics? The mid-latitudes? And the polar latitudes? I'm interested in both the mean and variance of the precipitation.
15
votes
1answer
300 views

When a tectonic plate subducts, does any of the subducted material melt, or is it just the mantle above the subducted slab that melts?

I know that water released from oceanic crust causes melting of the mantle in subduction zones, but does any part of the subducted slab melt as well - such as the sediments on the slab or the basalt? ...
8
votes
1answer
9k views

Why does the wind periodically change direction?

Image Subtitle: Wind going across the page - and changing direction To clarify, imagine you were sat in a boat in the middle of a lake recording the wind direction every minute. You notice that the ...
7
votes
1answer
91 views

Why is Arizona the fastest-warming state in the U.S. (since 1970)?

The states that have warmed the most — whether you look at the past 100 years or just the past 40 — include northern-tier states from Minnesota to Maine and the Southwest, particularly Arizona and ...
8
votes
1answer
415 views

How does the amount of mass in an atmosphere affect the seasonal changes and dynamics of the planet's climate?

I was thinking about this question, which may turn out to be simple, about climate dynamics: How does the amount of mass in an atmosphere affect the seasonal changes and dynamics of the planet's ...
9
votes
1answer
375 views

What geological processes can cause local biases in the fossil record?

What are the main geological processes that can cause local biases in the fossil record, e.g. when comparing species diversity or species occurances in different areas from the same time period? I ...
12
votes
2answers
3k views

Why is colored seismic inversion called 'colored'?

One of the seismic inversion algorithms is called 'colored' inversion. It is performed in the frequency domain and the point is in building an operator that directly transforms a seismic trace into ...
7
votes
1answer
1k views

Golden and red colored light even after sunset

I heard about the golden hour, but yesterday I saw golden and red colored patches in the sky even after sunset. Why does it happen? And I would like to know more about the science behind the golden ...
7
votes
1answer
190 views

Why is the warm phase of the Pacific Decadal Oscillation associated with stronger El Niños?

This is a question inspired by the post at Cliff Mass Weather Blog: "Is a Super El Nino Coming Next Winter?". There is something else. You ever hear of the Pacific Decadal Oscillation? This is ...
12
votes
3answers
288 views

What are the scientific consequences of the lost of the Nereus submersible?

The Nereus submersible was lost at sea while exploring the Kermadec Trench at 10,000 meters during a May 2014 research cruise. During its life, it was planned for the ROV to help investigate the ...
9
votes
0answers
94 views

How much does the Meridional Overturning Circulation strengthen the Gulf Stream?

While the Gulf Stream is a western boundary current (WBC), one professor told me that the Gulf Stream is stronger than it should be just by using theoretical calculations of WBC. How much is the heat+...
11
votes
3answers
1k views

Where to find an accurate Mercator Projection world image?

I'm sorry if this doesn't fit "Earth Science" too well. No idea where else to ask this! Can anyone help me find an accurate world map in Mercator Projection? It doesn't need political borders or too ...
11
votes
1answer
118 views

Why would a suite of related rocks have one anomalous sample?

I have a suite of rocks that have nearly identical major element chemistry, but a single sample has quite different trace element concentrations. All the rocks are trachydacites. I know the analysis ...
10
votes
1answer
479 views

How was the Marinoan Glaciation triggered?

The Marinoan Glaciation (a.k.a. Elatina Glaciation) was a glaciation that is thought to have occurred towards the end of the aptly-named Cryogenian period at ca. 650Ma. It is particularly known as one ...
12
votes
1answer
2k views

Is there any correlation between La Niña/El Niño and seismic activity?

I've read in the past that extreme precipitation levels may have an effect on seismic activity, and wondered if anyone has ever analysed the La Niña / El Niño cycles to see if there are any ...
13
votes
2answers
2k views

What is the difference between a high-resolution model and a regular model run?

So we have high-resolution models like the HRRR (High Resolution Rapid Refresh). But what exactly is the difference between a high-resolution model and a regular model? I realize that the higher ...
10
votes
1answer
160 views

Sediment layer chronology

In the new Cosmos series, Neil DeGrass Tyson in explaining different ways the age of the world has been determined, shows how sedimentary layers at the Grand Canyon are a fossil record of a lot of the ...

15 30 50 per page