Hot answers tagged

50

It's the international date line and marks the boundary between the time zones that are +12 and -12 hours from UTC / Greenwich. It should follow the +/-180 degree meridian line, but zigs and zags to include territories or islands within a "day" thus the Aleutians islands are in the same time zone as the Hawaiian islands.


42

If we consider only the magnetic field generated by natural sources, and not the ones generated by human activities. The general trend is that higher intensities of the magnetic field happen close to the magnetic poles. However, this is just a general trend. The southern hemisphere experiences the highest magnetic fields intensities, reaching over 65,000 nT, ...


38

Mkennedy's answer is right at identifying that line as the international date line and explaining how it works. However, I'd like to add on the main weird points of the line. North to south: In the Bering sea, the line bends eastward to include all Russia in the same side, and then it bends westward to include the Aleutian islands on the same side as Alaska ...


22

Absolutely not. First of all, "rare earth magnet ore", meaning the ores of metals like neodymium (Nd) and samarium (Sm), is not magnetic at all. It only becomes a magnet once you make a magnet out of it. For example, one such magnet is Nd2Fe14B and it only becomes a magnet after neodymium is combined with iron and boron. Naturally occuring neodymium ore ...


15

Yes, there are many. According to the seafloor topographic data of ETOPO (1 arc second resolution), and the Exclusive Economic Zones (EEZ) database of marineregions.org. There are at least 157 seafloor features higher than -100 m (closer than 100 m to the sea surface). With that data, I made the following figure that shows: ETOPO topographic data All EEZ ...


13

Since it is not specified in the question (and to complement the other answer), the strongest magnetic fields on Earth are not naturally generated, but artificially. The current world record holder seems to be the National High Magnetic Field Laboratory (NHMFL) in Los Alamos, USA, with a magnetic field strength of about 100T (so about two million times ...


13

So here is the way I do that personnally with NaturalEarth data and R (but you can do something similar i m assuming with any programming language that can deal with GIS or any GIS software): Fist download and unzip the file: download.file("http://www.naturalearthdata.com/http//www.naturalearthdata.com/download/10m/physical/ne_10m_coastline.zip", "...


13

Checking the Wikipedia page on underwater volcanoes and listing them by height, I think the best candidate is Vema Seamount. Vema Seamount is in international waters and its shallowest point is at 11 meters from the surface. It is so shallow that it represents a navigation hazard.


12

To answer the first question, yes, there are maps showing the seasonal temperature variation, for example here Unsurprisingly, the equatorial areas have the least variation because the angle of the sun relatively to the earth changes the least with seasons. Regarding nice weather- I have worked as a geologist in northern South America and the Caribbean. ...


11

Yes. Every equal-area map displays all countries (and other areas) in their correct relative size. Inevitably, they don't show the correct shape (unless you're looking at a globe). Personally, my favourite projections are pseudocylidrical equal-area projections, such as: Mollweide projection Eckert IV projection Tobler hyperelliptical projection There ...


11

One standard that has be used by the USA is to measure the distant between points on the coast at intervals of 30 latitude minutes, as measured on a 1:1,200,000 scale map. See chapter 5 of Measurements from Maps: Principles and Methods of Cartometry by D. H. Maling for further information and other standards that have been used.


11

No. Cosmic radiation are high-energy particles that create particle showers high up in the terrestrial atmosphere. Those particle shower are heavily beamed downwards, and although in principle some secondary shower products feel the local magnetic fields, effectively are not affected by the natural terrestrial field, let alone weaker local fields. Those ...


8

A rough idea, using the Lambert Conformal image at the Cartopy projection list and Gimp: The gold area should be the overlap. So basically parts of South America with Indonesia and SE Asia... and Antarctica with the far northern islands of the northern hemisphere, plus a few smaller areas from islands like New Zealand and Hawaii and even smaller. That ...


8

You can use Generic Mapping Tools (GMT): http://gmt.soest.hawaii.edu/ It's a command line tool for (among other things) plotting maps and geographical data. Works best on Linux/Mac but also on Windows. Here's an example. Running this code generates a map: gmt pscoast -R0/360/-80/85 -JM20 -B20/10 -Di -Glightbrown -Slightblue -Wblack > merc.ps And this ...


8

It is an extinct volcanic crater. The location is not listed as one of the active volcanoes in Madagascar. Simplified geologic map of Madagascar (reference) shows the crater to be mapped as basaltic / Gabbro lava,


8

Soil color is largely determined by it's composition. There are three main components in soil: Gravel, sand, and silt. In essence, the type of stuff you find in sedimentary rocks. Usually, this is mostly silicate minerals like quartz, feldspar, and mica, and is usually pretty bland in terms of color. In theory, certain silt minerals (olivines for example)...


8

Yes, there are maps that map out variations in the earth's magnetic field, example here http://science.gc.ca/eic/site/063.nsf/eng/97358.html. The large variations are primarily due to the presence of ferric materials, ie large deposits of material like magnetite. There are no areas of rare earth magnets as far as I know, given that rare earth magnets are ...


7

Google Maps and MapQuest have gathered data and information through subcontractors and their own internal efforts. Their information is proprietary and is very hard to gain access to (and most methods of scraping this data would violate their Terms of Service). It's generally not considered a reliable source for getting anything beyond geocoded addresses. ...


7

Your question has an incorrect assumption built in. Near surface ground water temperatures are not generally colder, but rather reflect the average annual temperature. This will be colder than surface temps in summer, but warmer in winter. There is an an additional effect if your rainfall isn't evenly distributed over the course of the year, as percolating ...


6

It's almost certainly a difference in the UTM zones. In most zones, the minimum easting value is 160,000 mE and the max is 834,000 mE (at the equator). People sometimes use the 'wrong' zone (i.e. not the zone that the location is actually in) if it's more convenient to use a neighbouring zone for some reason. For instance, maybe I have coordinates for 100 ...


6

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 great help here, did you manage to do that? 2. What type of fold is shown on the map. What is the definition of a syncline and does your interpretation agree ...


6

It looks like your coordinates are written in decimal degrees but with the decimal points omitted. 34.144442 -118.654084 corresponds to 34°08'40.0"N 118°39'14.7"W. Google maps shows this to be a location just outside LA.


5

I can't be sure, but I strongly suspect that the radial lines in the first two images are the result of a bug in the software used to draw the map, probably resulting from vector polygons that are described in an inappropriate coordinate system going around, or too close to, the south pole. It's impossible to guess at the meaning of the blue lines in the ...


5

If you're looking for a cool, well detailed map of convection cells that looks like a modern weather map....forget it. What you're looking for has been notoriously difficult to produce, if not impossible. Even the most advanced seismic tomography techniques using seismic wavespeeds can only resolve mantle "features" thousands of kilometers in scale, but ...


5

Map elements and signatures Every signature used in the map (except of elevation contour lines) has to be explained in the legend. For example, the dashed line is not explained. Your map needs a scale bar or at least a numeric scale. Look for better signatures for the street/path and choose one for the river. To complete it, a topographic map is always ...


5

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 stratification. On the western side the diorite-shale subcrop is higher, suggesting about an 80 metre downthrow to the east. The aplite boundary shows no curvature in ...


5

For sure this is not available. To create those maps takes several dozens Earth orbits by GOCE (one orbit ~90 minutes) and possibly many more to bring up the signal to noise Which gravitational features would you expect to vary significantly on any human timescale, so that creating such a scan would make sense? This does not mean however, that no ...


4

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 side of the fold axis are more than at right angles to each other, indicating an open fold of about a 110 degree deformation. Now consider the basalt dykes: ...


4

Natural Earth is a public domain, map dataset available at 1:10, 1:50, and 1:110-million scales. Announced at the 2009 NACIS (North American Cartographic Information Society)annual meeting in Sacramento, California, the goal is to give cartographers an off-the shelf solution for creating small-scale world, regional, and country maps. It has several ...


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