Detecting a Gully/Wash
Our first week ‘Out Bush’ was an eye opener for everyone, for me because I was seeing my homeland through the eyes of others and for Chris and Steve because even though metal detecting is a familiar pastime the world over, Australia’s particular brand of geology is pretty unique due to the sheer age of our rocks and more particularly the oxidisation of those rocks through eons of weathering.
Chris drove this home to me a number of times through the ‘getting to know each other’ stages of our trip when out of interest I pointed out various rocks scattered about the landscape which upon initial investigation generated a remark from Chris that he was not exactly sure, but it could be such and such... followed once again by mutterings about the geology being ‘so weathered here in Australia!’
Thinking this might be a good time to expose the guys to something more recognisable I decided to take them to a virgin gully/wash I found in 2009. This area is difficult to get into, I found it by chance late one afternoon when traversing the area by quad so only had a vague impression about following a fence line with the 4x4s to get close to the area in question, this ended up in an adventurous cross country tour with some wildlife thrown in along the way.
Steve was beside himself when we finally arrived at the location especially when he saw the riffle like schist rocks running across the creek creating perfect trap points for gold to settle. The area was reasonably quiet mineralisation wise, so I suggested they detect in the Sensitive Extra Timings located under the Special heading of the GPX 5000 (make sure you also select Special at the Timings switch on the detectors front panel). Because it was a small area Steve decided to head upstream where the gold seemed to have sourced after I managed on camera to glean some excellent insights on the 'where’s and why’s' he detects where he does when in a gully/wash.
Very soon Chris was knocking out little nuggets hidden in amongst the rocks using a 14” elliptical Monoloop coil, what was surprising was even though the ground was quiet there was still a considerable difference in signal response using Fine Gold compared to Sensitive Extra, so he ended up reverting to those Timings using Fixed Ground Balance and an elevated Gain setting (maybe this is why I missed those nuggets back in 2009 as I had only ever detected this wash using Normal Timings?). Not long after Steve came grinning back on down the creek with a decided swagger that could only mean one thing, I’d missed a few pieces high up in the drainage system. Sure enough he’d found one of the prettiest nuggets for the trip; hopefully he will forward me an e-mail sometime soon with a picture attached of the nugget all cleaned up.
It was so nice to take the blokes somewhere that was familiar to them and to also get a true impression of what they would be like on their own turf. Both Steve and Chris took to the little drainage like they had been there before; turning up nuggets in places I would never have given a second glance. I know from now on I’ll be paying more attention to Green Schist gullies and more particularly doing a bit of rock rolling in the process. Why don’t you take a look at ‘The West Australian Adventure’ video I shot of the day for a little more insight into the whys and wherefores of Gully/Wash hunting from a couple of masters at the game?
As always I encourage robust discussion with Minelab Treasure Talk readers.
Jonathan Porter
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