Originally Posted by compressed View Post

the rock/earth below us occurs in layers. over time those layers get distorted/twisted, move around. as a consequence, a layer of something valuable (something with high gold value, for example) can become a very complicated shape underground, and structural geology is about trying to figure out what's happened and where the layer is/its extents.

when you drill a hole, the hole almost never goes straight. to model the drillhole, you get a series of angle measurements down the hole (azimuth and dip/inclination), that give you a reasonable mathematical representation of where it went (it's never 100% accurate).

when you pull the drill core out, those layers/features will show at various angles, both due to the direction the drillhole went, and the deformation over time. there are two angles that can be read off the core (alpha and beta) using a reference line.

so what you end up with is 4 angles at a given depth - 2 representing the drillhole direction, 2 representing the feature's relative direction. you use those 4 to figure out what the true feature direction was at that depth (or the apparent direction based on some arbitrary plane).

what you've got there in that image are triangles with one edge elongated past the triangle shape. the long edge represents the strike (basically the angle from north) of the rock feature at that point, while the triangle represents the angle it dips down. the colours are some sort of colour coding based on something at that depth - perhaps lithology, maybe an assay value. i think for that screenshot (which i made a few years ago) i may have used either the alpha or beta angles, which an actual geologist would never do, but it looked more interesting that way (if i'd used lithology, there might have been only 3 or 4 different colours).

and yes, i did write this to avoid doing some tedious database code. wohoo.

Damn, I remember in a former life, us undergrads were out in the field with a post grad showing us how to take dips and strikes. She didn't know shit, so we had to keep two sets of figures, hers and the real ones.

This is in a different league to what we were doing though.

Not relevant to the thread, just brought back some fun memories.