Field Station: Position, Compass and the Ground Around You
Stand at an outcrop and the phone tells you where you are, which way you face, the dip of the bed, the weather to expect and what the ground around you is made of.
A complete field station on the phone. The position is averaged from many satellite readings and given in degrees, degrees–minutes–seconds and UTM, with the elevation above sea level. The compass and clinometer work in three holds: flat (the direction of the top edge, with a level bubble), upright (the direction the camera looks and its tilt) and laid on the bed (dip, dip direction and strike), in magnetic and true north; readings are locked, recorded and sent to the stereonet. The station sheet adds the weather for 24 hours with the hour rain or a storm is expected, heat, frost, gusts and sunset; the nearest road, track, river, stream, spring, village, named peak and cave with distance and bearing; the geological unit underfoot and around with the colours, rocks, fossils and features of the Iraqi formations; groundwater indications; and the nearest active faults, on a map and a one-page station card.
Overview
Every field day is a series of stations, and at every station the geologist asks the same questions: where exactly am I, how high, which way is the bed dipping, what formation is this, what should I look for, and will the weather let me finish? This tool answers them in one place and keeps the record.
The position, compass and clinometer need no network. The weather, nearest features and geological map are read when there is a connection; areas saved beforehand with the geology camera supply the elevation, units and faults in the mountains.
What you enter · What you get
What you enter
- Position from the phone (averaged) or a tap on the map
- Compass and tilt of the phone in one of three holds
- Geological map unit layer (optional)
What you get
- Position in degrees, DMS and UTM with accuracy and elevation
- Magnetic and true heading, tilt, dip, dip direction and strike
- Recorded readings (CSV) and planes sent to the stereonet
- Weather for 24 h with rain, storm, heat, frost, wind and sunset alerts
- Nearest road, stream, spring, settlement, peak and cave
- Geological unit, formation colours, rocks, fossils and features to look for
- Groundwater indications and nearest active faults
- Station card figure
How it works in the field
Method and equations
Averaged position
Satellite fixes collected for up to 30 seconds are weighted by the inverse square of their reported accuracy; the result is converted to UTM with the Krüger series.
Heading in the three holds
The rotation matrix R(α, β, γ) of the device orientation gives the direction of the top edge (flat), of the back camera (upright) and the screen normal (on the bed). Declination from the IGRF model converts magnetic to true north.
Dip and strike
With the phone lying on the plane, the upward normal n gives the dip and the dip direction; the strike follows the right-hand rule.
Groundwater indication
The height of the station above the nearest mapped stream, from the elevation model, is combined with the aquifer behaviour of the lithology. The water table follows the ground in a subdued form, so low ground near streams is usually shallow.
Accuracy and error limits
- Averaged position ±3–10 m in the open, worse under cliffs and in narrow valleys; GPS height ±10–20 m, the model elevation ±5–10 m. Compass ±5–15° depending on the phone and nearby metal, about ±3° after calibration away from vehicles; dip ±2–3° on a flat surface. The weather is a forecast, best for the next few hours. Nearest features depend on what is mapped and may miss new roads or small springs. The geological unit is as good as the regional map.
- What is not covered: the actual depth of the water table (no point data exist; only indications are given), the condition and safety of roads, private land, and features smaller than the map shows. Phones without a magnetometer, and most laptops, have no compass.
- To reduce the error: stand still in the open for the position; calibrate the compass with a figure of eight and stay a few metres from the car, the hammer and the keys; lay the phone on a notebook over rough bedding; check several readings against a real compass-clinometer at the first stations; confirm the unit with a lens, acid and fossils; and measure groundwater with a vertical electrical sounding or at a nearby well.
Who uses it
Standards and references
- W3C (2023). DeviceOrientation Event Specification. World Wide Web Consortium.
- Alken, P. et al. (2021). International Geomagnetic Reference Field: the thirteenth generation. Earth, Planets and Space, 73, 49.
- Karney, C.F.F. (2011). Transverse Mercator with an accuracy of a few nanometers. Journal of Geodesy, 85, 475–485.
- Allmendinger, R.W., Siron, C.R. & Scott, C.P. (2017). Structural data collection with mobile devices: accuracy, redundancy, and best practices. Journal of Structural Geology, 102, 98–112.
- Novakova, L. & Pavlis, T.L. (2017). Assessment of the precision of smart phones and tablets for measurement of planar orientations. Journal of Structural Geology, 97, 93–103.
- Haitjema, H.M. & Mitchell-Bruker, S. (2005). Are water tables a subdued replica of the topography? Ground Water, 43(6), 781–786.
- Zippenfenig, P. (2023). Open-Meteo.com Weather API. Zenodo.
- OpenStreetMap contributors. OpenStreetMap.
- Peters, S.E., Husson, J.M. & Czaplewski, J. (2018). Macrostrat: A platform for geological data integration and deep-time Earth crust research. Geochemistry, Geophysics, Geosystems, 19(4), 1393–1409.
- Styron, R. & Pagani, M. (2020). The GEM Global Active Faults Database. Earthquake Spectra, 36(1_suppl), 160–180.
- Jassim, S.Z. & Goff, J.C. (eds.) (2006). Geology of Iraq. Dolin, Prague and Moravian Museum, Brno.
- Coe, A.L. (ed.) (2010). Geological Field Techniques. Wiley-Blackwell.
At a glance
- Category
- Field geology
- Runs on
- Phone, tablet and desktop browser
- Export
- Station card as PNG, JPG and PDF; readings as CSV; position shared as text; planes sent to the stereonet; full PDF report
- Access
- Free
Run this survey on your next site
All 64 tools, report export and the AI assistant come with one subscription.