[HOT] open geology map

Christian Ledermann christian.ledermann at gmail.com
Sun Mar 15 15:09:09 UTC 2015

If you are looking for a collaborative approach to collect/maintain
the data have a look at http://geogig.org/
I think that could be better suited for "your kind of data" than the OSM format.

just my 2 cents.

On 14 March 2015 at 17:53, john whelan <jwhelan0112 at gmail.com> wrote:
> So probably the best place for it would be a separate database that could be
> combined with OSM data.  There is no reason why it couldn't use OSM format
> and tools such as JOSM though.
> I worked in a library for a while and we had a theory that if you asked five
> classifiers how to classify a book you'd get six different answers.
> Cheerio John
> On 14 March 2015 at 13:38, Charlotte Wolter <techlady at techlady.com> wrote:
>> Sander,
>>         I agree with most of your points and would like to add that
>> surface geology is a highly specialized field requiring a great deal of
>> expertise. I'm a geology buff myself, and there is no way I would attempt to
>> map that. Also, there often is strong disagreement among geology
>> professionals about the nature and dating of rock units, disagreements that
>> make some of our set-tos about how to code sound trivial.
>>         Also, there generally is a lot of local information about
>> landslides and tsunami risk, courtesy of the USGS, though sometimes it is
>> ignored. In Los Angeles, tsunami-prone areas are signed along major roads,
>> as are the areas subject to debris flows. The recent deadly landslide in
>> Oregon was in an area known to experience landslides, but apparently the
>> risk was not widely publicized.
>>         Tsunami risk, perhaps, could work as an overlay, and I believe
>> that data is available from the USGS.
>>         But, generally, I think this whole area may be too technical for
>> widespread application in OSM, even though I would enjoy seeing it.
>> Charlotte
>> At 05:59 AM 3/13/2015, you wrote:
>> I think this suggestion belongs more on the general OSM talk or tagging
>> list than on the HOT list, but anyway.
>> There are already a number of ways to tag surface, like surface=*,
>> natural=*, landuse=*, landcover=*, ... Just read the wiki about those (f.e.
>> http://wiki.openstreetmap.org/wiki/Key:natural )
>> There's also a convention in OSM about sub-tagging. F.e. you could tag
>> natural=rock + rock=sandstone
>> Thus I guess most of what you want is already possible in OSM. You should
>> only try to add a few more specific conventions (f.e. about the types of
>> rock).
>> I probably don't really get your 3D attempts, but the general concensus is
>> that it's hard to get in certain places, and thus you can't make a uniform
>> map of heights or angles. As such, OSM contains no height or slope data
>> (apart from the elevation of some peaks), but leaves this to professionals
>> (such as the NASA). It isn't so hard to extract a general slope from good
>> precision elevation data, so there's no point in including it directly in
>> OSM data (with the right preprocessor, it can get rendered on the map
>> anyway).
>> So that doesn't belong in OSM, but it isn't the biggest problem IMO. The
>> biggest problem I see in your attempt is ignoring that OSM is a crowdsourced
>> effort. For crowdsourcing, you need a crowd, and that crowd is most easily
>> found in populated places. Your effort seems to focus on areas with a low
>> population (a city isn't very vulnerable for a landslide). But sadly,
>> there's no crowd around there, so the most we would be able to do is some
>> mapping from aerial pictures. This shouldn't hinder you from starting the
>> project, but you shouldn't have very high expectations from it.
>> Regards,
>> Sander
>> 2015-03-12 22:03 GMT+01:00 Hazel <hlhj2 at srcf.net>:
>> Dear All,
>> Can we again discuss putting geological data into OSM? Specifically, I'd
>> like a recommended way to tag fault lines and surface geology polygons.
>> This e-mail assumes the reader knows nothing of geology, apologies to
>> everyone else.
>> First, the usecase: geological data saves lives in natural disasters, it
>> is useful for common activities like agriculture, and it is interesting in
>> its own right. It can also be usefully collected by amateurs.
>> I am not suggesting that OSM should produce disaster risk maps, or
>> recommendations for farmers. I am saying OSM could collect the data that
>> would allow experts to quickly and easily make these things.
>> Using OSM contours, they can work out areas of flood risk and tsunami
>> escape routes. Using contours and and basic geological information, they can
>> work out areas of landslide risk (landslides kill more people than volcanoes
>> or floods or earthquakes, but they kill a few dozen at a time). If we map
>> faults, they'll know more about where earthquakes are likely to happen (you
>> know the photos of roads after earthquakes, offset by a few centimeters? The
>> fault is the plane where the offset happens, and earthquakes use the same
>> faults over and over again). If you map areas of shallow bedrock vs.
>> unconsolidated sediment, you know which areas may suffer soil liquifaction
>> in an earthquake.
>> https://en.wikipedia.org/wiki/Soil_liquefaction soil liquifaction
>> Technical infodump:
>> To make a geological map, you map areas with similar surface rock or
>> sediment2. You describe them (anything from field IDs like "greenish rock
>> #2" to detailed technical descriptions) and give them proper names (e.g.
>> "the Tunbridge Wells Sand Formation").
>> Having mapped the boundaries between different rock types, you can also
>> trace faults and the line of folds in the rocks. These all obviously exist
>> in 3-D, but are usually represented on 2-D maps. Just mapping the 2-D trace
>> is enough for many purposes.
>> If you want to add more information about the third dimension to a two-D
>> map, there are conventions for that. You specify a line (along the axis of
>> the fold, or on the steepest line down the fault plane or boundary plane).
>> You map the direction of this line. Then you measure the angle between the
>> line and the horizontal, and write in on the map (next to standard symbols:
>> for a plane, a T-shape, and for a fold axis, an X with two or three of the
>> lines turned into arrows pointing in the two or three downhill directions).
>> Plane:
>> http://web.arc.losrios.edu/~borougt/StrikeAndDip.jpg
>> Fold:
>> http://bc.outcrop.org/images/structural/press4e/figure-11-16b.jpg
>> Planes on either side of a fold:
>> http://courses.missouristate.edu/EMantei/creative/GeoStruct/strkdip.jpg
>> This is actually fairly easy to explain in 3-D, but not in 2-D, and I
>> don't know of a good video. We could make one.
>> Example:
>> Let's look at the Weald area of the UK, since it is well-mapped.
>> Read:
>> https://en.wikipedia.org/wiki/Weald#Geology
>> Terms:
>> "Lower Cretaceous" and "Upper Jurassic" describe age (lower means older)
>> "rocks", "chalk" and "sandstone" describe rock type
>> "sands" and "clays" describe sediment type
>> "Purbeck Beds", "Ashdown Sand Formation" and so on are proper names of
>> groups of rocks/sediments. These names are hierachical, like taxons, and are
>> in databases (for the Chalk Group that forms the White Cliffs of Dover:
>> http://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=CK).
>> The cross-section may help make the 2-d map make sense.
>> To see how faults and folds (synclines/synforms, that sag, and
>> anticlines/antiforms, that hog) are mapped as lines, see this map:
>> https://commons.wikimedia.org/wiki/File:Geologic_map_SE_England_%26_Channel_EN.svg
>> (just gives rock ages, not type).
>> Faults are usually much more obvious on small-scale maps than they are on
>> this map.
>> For sediments, there exist multiple soil classifications, with mappings
>> between them, and OSM could support them all, but the classes we have (sand,
>> gravel...) would be enough to start with.
>> Examples:
>> https://en.wikipedia.org/wiki/Australian_Soil_Classification
>> https://en.wikipedia.org/wiki/USDA_soil_taxonomy
>> etc.
>> QGIS is increasingly used for geological mapping, so it works increasingly
>> well with many other geological tools. QGIS is already well-integrated with
>> OSM. The barrier for geologists new to OSM to upload their maps is therefore
>> low. Classes of students could do it.
>> http://wiki.openstreetmap.org/wiki/QGIS
>> End infodump, requests for clarification and corrections welcome.
>> Could anyone suggest a set of minimal changes that would make it possible
>> to enter data like this? As I said, just having a recommended way to enter a
>> surface geology polygon, a geological contact line (between two polygons),
>> and a fault line (with optional dip direction and inclination) would be very
>> useful.
>> Pseudo-3-D perfection would also allow keeners to input the contact
>> between two rock formations (line, with dip direction and inclination) and
>> input folds (line, with dip inclination), but this can also wait.
>> Regards,
>> Hazel
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>> Charlotte Wolter
>> 927 18th Street Suite A
>> Santa Monica, California
>> 90403
>> +1-310-597-4040
>> techlady at techlady.com
>> Skype: thetechlady
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Best Regards,

Christian Ledermann

London - UK
Mobile : +44 7474997517



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