If you are a prospector (I’m guessing you are since you are reading this) and you haven’t heard of strike and dip then you need to read this article!! While strike and dip is primarily used by geologists, prospectors use it as well, and it can be vitally important to know if you want to be successful at locating new gold rich hotspots that havent been hit before. If this sounds like something you want to know then read on, and watch the corresponding youtube video
Strike and dip is used when describing the orientation of geologic formations, bed and strata, including gold bearing veins. When talked about in geologic reports and paper it will be generally given like this: N35E, 60SE, with N35E being the strike or direction that the vein is running, and 60SE being the dip or the angle from horizontal at which the vein goes into the ground. You can see this being demonstrated in the below illustration.
Another place that the prospector will come across strike and dip is on geologic maps when they are doing research. Strike and dip will be displayed as such on a geologic map:
With the longer line showing the strike and the tick off of it showing the dip with 60 degree being the dip. Below is an example of it on a geologic map.
So in the above example there are two strike and dip symbols both showing near the same strike of approximately N10E, with similar dips of 30W and 31W.
Hopefully the above description has helped with understanding the basics of strike and dip. Now to move on to useful application of this for the gold prospector.
So I know many prospectors use maps that show the various locations of old gold mines, such as the MRDS overlay for google earth. They will then get access to these locations and go into the field near the old gold mine and be baffled when they find little to no gold. Sometimes this can be due to the fact that the stream they were prospecting while close to the gold mine and its vein, the stream and its valley did not intersect that particular vein system.
So let’s use an example with a topo map. The gold mine location at the end of the green arrow. The prospector used the MRDS to locate the gold mines location but did not dig any deeper into the research to discover that the strike and dip of the vein was documented in an old mining document about that particular mine.
Our prospector dug at the end of the blue arrow, by his estimation it should be a good location because it’s only a few hundred yards from the mines location. But this particular vein (red line) has a strike and dip of N45E, 80SE. This means that while the location that he panned was close to the mine, you can see that that vein does not cross that part of the stream. This means that little to no gold from that vein system would be present at the location he panned.
Had he dug a little deeper into his research he would have found the strike and dip of the vein and been able to deduce that the stream section highlighted in yellow would be the best possible spots to test pan. This is because those portions of the streams and stream valleys are either down slope of the vein or are directly cutting across the vein. This leads to the gold eroding from the vein ending up in those sections of the stream.
This little bit of extra knowledge and research can be the difference between the prospector striking out or hitting it big.
That’s it for part one of this series. More to come using the same map that is pictured above.
Please check out my youtube video that corresponds to this post. (https://youtu.be/t2Xv36BXPaU).