Magnetics is the dataset every exploration geologist is handed and few are taught to read. This course teaches it the way exploration asks the questions: where would you drill, and why would you miss? Seven modules and about 6 hours, in your browser, on real ground mapped by the Geological Survey of Western Australia.
Opening soon. Join the waitlist and we will email you when it opens. See what is in it
Module 1, lesson 2 opens on a decision: two vertical holes to find a pipe near Geita, in Tanzania.
Every lesson starts with a decision
Site the hole first. Then find out why it missed.
Each lesson opens with a choice to make before anything is explained: count the dykes, site the hole, pick the target your rig can reach. Short sections then explain what you just saw, with figures you work yourself.
Drag the Earth's field from Kalgoorlie to Bamako and watch an anomaly move off the rock that makes it.
Type in your own project's coordinates, widen a survey's line spacing, turn up a rock's remanence.
No maths to do. The physics is in the figures, and you learn it by moving them.
Questions and challenges are scored as you go, and each lesson ends with what to remember and tips from the field.
The same plug and dykes, flown at Bamako. The plug reads as a low, and the north-south dyke all but vanishes.
Real ground
GSWA's magnetics, with the geology over it.
Every idea is shown on ground a geologist recognises: the Geological Survey of Western Australia's open data, with its mapped geology laid over the grids.
The Kambalda Dome and its nickel, the Widgiemooltha dyke swarm, and St Ives gold beside the Boulder-Lefroy Fault.
Gold at Mount Magnet and Wallaby, lamproite pipes in the Ellendale diamond field, and the iron ore at Newman.
Lithium pegmatites at Mt Marion and Mallina, and the Mt Weld carbonatite under its cover.
Point at a unit for its name, click it for GSWA's description and age, and switch between its contacts and the full map.
Radiometrics and gravity beside the magnetics, where they see what it cannot.
GSWA magnetics over Kambalda, with the contacts of GSWA's 1:100 000 geology.
Your interpretation, scored
Draw it in Lightbox. See what you found.
The exercises open in Lightbox with the grid loaded and a card of steps beside it. Draw your interpretation, then check it.
Check my interpretation scores your lines against the answer: what you found, and whether you drew it as the right type.
What you have not drawn yet is marked on the map. Check as often as you like.
Show the answer when you are ready, and compare it with your own lines.
Each module ends on a capstone: a whole block to interpret, from the grid to a sequence of events.
Exercise 1 in Lightbox, with its answer shown over the grid.
What is in it
Seven modules, about 6 hours.
Work through them in order, at your own pace. Each lesson takes 5 to 20 minutes, and your progress saves as you go.
Module 1Reading a magnetic grid1 hour 15 min, 5 lessons
Learn to read a magnetic grid, from what its numbers mean to a full interpretation of a 20 km block. It takes about an hour and a quarter in your browser, and every lesson asks what exploration asks: where would you drill, and why might you miss?
The picture is a choice15 min Colour a grid so it shows everything, and know what a survey can miss
Why the anomaly is not over the rocks20 min Say where the rock is under any anomaly, anywhere on Earth, and when reduction to pole cannot help
Which grid for which question15 min Pick RTP, 1VD, tilt, analytic signal or upward continuation for a job, and take a rough depth
When the RTP lies10 min Spot remanent magnetisation, and draw a reversely magnetised dyke
Your first interpretation15 min Interpret a block from TMI to a sequence of events
Module 2Can you trust the grid?40 min, 5 lessons
Every grid you are handed was flown, levelled, gridded and merged by someone else. This module shows how to tell what the survey did to it from the geology: stripes, joins, missing detail, and noise from powerlines and sheds. It also shows what the grid maps, which is one mineral and what happened to it, not rock names.
Stripes along the lines5 min Tell flight-line stripes from geology, and know what levelling and Remove line noise each take off
One grid, many surveys10 min Find the joins in a merged grid, and judge what its surveys could see
Not geology10 min Recognise culture, and choose the survey that can see your target
What makes a rock magnetic10 min Say what makes a rock magnetic and what takes it away
Weathering, from the top down5 min Tell weathered cover from bedrock, and read the magnetism the cover makes
Module 3Structure in the magnetics45 min, 4 lessons
This module reads the structure in a magnetic grid: the faults, shear zones and folds that control where gold and nickel sit. In under an hour you go from spotting a fault to putting a block's history in order.
Where things stop and shift10 min Find a fault, say which way it moved, and tell strike-slip from dip-slip
Corridors where the magnetite goes10 min Tell a shear zone from a reversed dyke, and read its sense from the drag
Folds in the form lines15 min Trace a fold, say which way it plunges, tell an antiform from a synform by its dips, and an anticline from a syncline by its rocks
Putting the structure in order10 min Interpret a structure block and put its history in order, including what cannot be told
Module 4Depth, dip and shape40 min, 5 lessons
A target on the map is half an answer. Before you drill, you need to know how deep it is, which way it dips, and where to collar a hole that cuts it squarely. This module teaches you to read those from the magnetics, to plan the hole, and to judge the 3D models other people make of your ground.
Shape from a profile10 min Read a body's depth and dip from a profile, and know what the profile cannot tell you
Aim the hole5 min Plan a hole that cuts a dipping body at the depth you want, at a good angle
Depth from the whole grid5 min Use the half-width rule, tilt depths and upward continuation together
Euler depths10 min Run Euler depths, choose the structural index, and tell solid depths from scatter
Reading an inversion10 min Say what an inversion can and cannot tell you, and what to ask whoever made it
Module 5Putting it with other data45 min, 4 lessons
The magnetics is one dataset. Many targets show better in another, or only when two are read together. This module puts the magnetics beside the radiometrics and the gravity, and teaches you which one sees what.
Which dataset sees it?10 min Say which dataset will see a target, and use it to find one
Radiometrics: the skin of the ground10 min Read a ternary, and tell residual soil from transported cover
Gravity: the weight of the rocks10 min Read gravity with magnetics, and say which rocks each pair of highs and lows suggests
One anomaly, three explanations15 min Keep every explanation of an anomaly in play until the data rule it out, map a block with five grids, and hand the interpretation over
Modules 1 to 5 teach you to read the rocks in the magnetics and the data beside it. This one asks where the metal is. Most lessons take one family of deposits, show what it does to the magnetics on modelled ground and then on real deposits, and make you choose where to drill before they explain. The last three take the deposits that are not magnetic, and what the magnetics can still find for them.
Peg and drill10 min Read a district for targets, peg it and drill it against a budget
Gold in the shear zones10 min Find where a shear zone crosses iron-rich rock, beside a big fault rather than on it
What the gold did to the magnetite10 min Know what real gold deposits do to the magnetics, and when a survey can see it
Nickel at the base10 min Find an ultramafic channel and drill its base, not its peak
Pipes and plugs10 min Tell a kimberlite from a gabbro plug, fly a survey that can see one, and read a real diamond field
Big systems10 min Pick out a porphyry and an iron oxide copper-gold system, with the gravity
Iron ore: the hole in the high10 min Look for enriched iron ore where a BIF goes quiet on a structure, and know why that is a tendency, not a rule
When the ore is not magnetic10 min Map where lithium pegmatites sit from the magnetics, and know what ground gravity sees of one
Follow the pegmatite you know10 min Use ground gravity to follow a lithium pegmatite along strike and across faults
Epithermal gold, zinc and lead, and carbonatites10 min Map the alteration around epithermal gold, the basin under zinc and lead, and a carbonatite under cover
Module 7Near the magnetic equator20 min, 3 lessons
Across West Africa's gold belts, the Earth's field lies almost flat, and it is little steeper over the Amazon, Ethiopia and southern India. Magnetic bodies read as lows, structures running north-south almost vanish, and reduction to pole stops being the answer. This module is the workflow for that ground: what the equator hides, which grids to use instead, and how to find what is not there.
What the equator hides5 min Predict which structures vanish near the equator, and find them anyway
Three ways to fix it5 min Choose between RTP, reduction to equator and the analytic signal
A workflow for the equator10 min Work a survey from the equator in order, and find a fault by what stops on it
Who it is for
For the geologist handed the magnetics.
Exploration geologists
You get grids with every project and an interpretation from a consultant. This is how to read them yourself, and how to question what you are given.
Graduates and students
The interpretation a geology degree rarely teaches, on real ground, with feedback on every exercise and a certificate for each module.
Anywhere on Earth
The physics works at any latitude. The lessons move the field from Kalgoorlie to Timmins and Bamako, and Module 7 is the workflow for ground near the magnetic equator.
Certificates
A certificate for each module.
Finish a module by reading every lesson, trying every exercise and finding 70% of the features in its capstone, and claim a certificate of completion in your own name.
It states the module and how long it takes, and carries a code anyone can check on NextMaps.
Add it to your LinkedIn profile from the certificate itself, or print it.
Log that time as professional development with your institute. It is a certificate of completion, not an accreditation.
A Module 1 certificate, for an example student.
Opening soon. Be first in.
Join the waitlist and we will email you when the course opens. Buying for a team? Email [email protected].
Geologists who work with aeromagnetic data and want to interpret it themselves: exploration geologists, graduates and students, and consultants who review other people's interpretations. No geophysics background is needed.
Do I need to know geophysics or maths?
No. The physics is in the figures: you move the Earth's field, a survey's line spacing or a rock's remanence and watch what the magnetics does. There are no equations to work through.
What do I need?
A web browser and a free NextMaps account. The lessons work on a phone; the exercises open in Lightbox, which runs in the browser, and want a laptop or desktop with a mouse. There is nothing to install.
Is it only about Western Australia?
No. The physics works anywhere, and the lessons move the Earth's field from Kalgoorlie to Timmins and Bamako. The worked examples are on Western Australian ground because the Geological Survey of Western Australia publishes its magnetics, gravity, radiometrics and geology openly, and Module 7 is the workflow for ground near the magnetic equator, such as West Africa's gold belts.
How long does it take?
About 6 hours over seven modules, at your own pace. Lessons take 5 to 20 minutes, and your progress saves to your account as you go.
Do I get a certificate?
Yes, a certificate of completion for each module you finish: every lesson read, every exercise tried, and 70% of the features found in the module's capstone interpretation. It states the module and how long it takes, carries a code anyone can check, and adds to LinkedIn. You can log that time as professional development with your institute. It is a certificate of completion, not an accreditation.
Is the data real?
Yes, wherever it can be: the Geological Survey of Western Australia's magnetics, radiometrics and gravity, its 1:100 000 and 1:500 000 geology and its database of mines, credited under each figure. The practice grids for the exercises are modelled from geology drawn for the course, so Lightbox can check an interpretation against a known answer, which no real survey can.
Who made it?
NextMaps, which makes Lightbox and the NextMaps map of Western Australia's mining tenements. NextMaps was built by Owen Hackenberg, an exploration geologist in Western Australia. Each module lists the published papers and books behind it.
Can I buy it for a team?
Yes. Email [email protected] with how many people, and we will set the team up.
