# Tag Info

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### What is the shortest path between two points on Earth's surface?

If you don't want to do the calculation yourself, you can use an online calculator like the one provided by NOAA. Alternatively, if you do want to do the calculation yourself you can use the ...

### What is the shortest path between two points on Earth's surface?

45E is directly opposite 135W. It's therefore obvious (hopefully) that the shortest path is straight over the North pole (which is at 90 degrees North). The path takes us round 120 degrees of the ...
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### How do I convert between different east longitude coordinates?

The database with the negative longitude angles is storing longitude as eastings and westings, whereas the other database is storing everything as eastings. It appears you prefer your data as ...
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### Making clouds for science project

To form a cloud, generally speaking, pressure does not play a significant factor (with the exception of the effect on temperature). If you want to prove that to yourself, go outside when it is foggy ...
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### The fertility of the soil

From this paper from 1958 (page 2), ... gaseous nitrogen of the atmosphere represents a vast store of potential fertility. It is not directly available to plants. Nitrogen-fixing bacteria, how- ...

### The free oxygen (O$_2$) in the atmosphere is largely a result of what process?

You are correct in thinking that oxygen comes from photosynthesis. In fact it is so much associated with photosynthesis, as opposed to any inorganic process, that the presence of oxygen in the ...

### Number of tectonic plates

This is primarily an exercise in interpreting a minimalist diagram. Believe me, you will have to learn to read even sketchier diagrams. That said, the test had the correct answer to the question. ...

### Take all the CO2 in the atmosphere and put it into a layer on the surface of earth, how thick would the layer be?

Ok, based on the comments above, this is where I am at... earth's radius is $6371 \text{ km}$ earth is a sphere There is approximately $3 \cdot 10^{15}$ kg of CO2 in earth's atmosphere The density ...

### Plotting a mineral stability diagram

Remember that you are concerned about stability fields. The lines on your stability diagram are the places where two minerals are in equilibrium. One one side one mineral will be more stable, on the ...
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### Interpreting a geological map

1. What is the youngest/oldest rock in the geological history of this map. Your approach is the right one but isn't the limestone underlain by something? Drawing the AB cross section would be of ...

### Why is there a seasonal cycle to the amount of CO2 in the atmosphere?

The magnitude of these seasonal variations differ from location to location. The graph below portrays variations in CO2 levels at Point Barrow Alaska (PTB), La Jolla California (LJO), Mauna Loa ...

### Where are the oldest igneous rocks found?

Zircons from Australia at 4.4Ga, and perhaps basalts from a Canadian island at 4.5Ga. It would interest you to know the quest of Boston University geochemist Matthew Jackson, who is searching for the ...

### The fertility of the soil

What does 'nitrogen' mean? Nitrogen might mean gaseous $N_2$. It might also mean compounds, which contain nitrogen, such as nitrate, ammonia and ammonium. $N_2$ $N_2$ cannot be metabolized by most ...
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### A sedimentary rock with only minerals

This is a really bad question, because all three can lack fossils, or all three can have fossils. The definition of "minerals" is also a bit unclear, because fossils are also made out of minerals. I'...
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### How to calculate hydrostatic equilibrium?

I am assuming you are asking for the case of sea level being 200m higher and in isostatic equilibrium. In that case we can make use of Airy's isostasy model: https://en.wikipedia.org/wiki/Isostasy#...

### Maps and Faults

There are no dips given, so you have to work by pure geometric deduction. The sediment subcrops on the east side all seem to be roughly parallel to the contours, which suggests near horizontal ...
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### How to graph gravity as a function of depth, given radius and density?

As long as we deal with a spherically symmetric planet, the mass of the shell above you does not influence the observed gravity; the little mass close by exactly cancels the large amounts of mass far ...

### Number of tectonic plates

There are three plates, because there are two plate boundaries (marked in blue): a convergent margin to the left, and a divergent margin to the right. Lithospheric plate #2 contains only oceanic ...

### Interpreting a geological map

From the dips it is obvious that the stratigraphic structure is a syncline, in which case you correctly deduce that the youngest layered rock is the mudstone. But look carefully. The dips on either ...

### Simplest formula of a calcium phosphate mineral?

Yes, you are correct in your calculation. However, the most common hydrated calcium phosphate in nature is indeed hydroxyapatite. Note that industrially, there are several other calcium phosphates (...

### Calculating magnetic declination for a non-axial dipole field

Inclination is given by $$I=\arctan(2\cot\theta)$$ where theta is equal to 90° minus the observer's latitude (in the Northern Hemisphere), therefore $$I=\arctan(2\cot(90-40))=59,21^\circ$$ To get ...
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### Relative dating of intrusion

It does seem like it's impossible to know unless you have additional information. However, I think there is a hint in there. See this white halo around the intrusion? My guess (and I could be wrong ...
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### To find hardness in Mohrs scale

Although this is a somewhat poorly researched question, I think there is an opportunity to make a nice point here. First of all, let's look at the Mohs scale: Talc Gypsum Calcite Fluorite (fluor)...

### Where can I find a shallow-water solver in MATLAB?

You aren't supposed to do link only answers, but that is really all this questions deserves. Did you look on Google? I did. https://people.sc.fsu.edu/~jburkardt/m_src/shallow_water_1d/...

### How do I find the horizontal pressure level that divides the atmosphere into 2 layers of equal mass?

I'll answer my own question. If there is hydrostatic equilibrium, then we have So, assuming that the surface pressure is p (in this case 1000hPa) and that the atmosphere's top has zero (0) pressure ...