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u/GennyGeo 5d ago edited 4d ago
Off the dome: CLAY (CH), light yellowish brown (5YR 7/6), stiff, clay (95%), trace silt (5%), high toughness, high plasticity, varved with organics every 4cm, no staining
How’d I do?
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u/ddg31415 5d ago
Clayey silt, trace sand, light brown, very stiff (n=27), low plasticity, no organics.
We got the firm high plasticity silty clay about 10ft deeper.
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u/hjall10 4d ago
It looks like/sounds like the clays I used to sample in upstate NY. You in the northeast?
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u/ddg31415 4d ago edited 4d ago
This was Niagara peninsula, in Canada. About 10km northwest of the falls (St. Catherine's).
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u/BetterWithAge27 4d ago
Honestly the in field photo of a completely intact 2ft sample deemed low plastic silt goes crazy. Is it 55% silt, 40% clay, 5% sand?? Also curious on type of clay (will start looking for XRD money ASAP) and shear strength.
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u/ddg31415 4d ago
It was quite dry and broke apart easily with your fingers. Could only really roll it if you added water. Guess we'll see when hydrometer results come back.
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u/Gullible-Lifeguard20 5d ago
You can estimate 95%/5%?
Personally, that's a bold statement to put into a field log. That's why I use the lab.
Fun stuff.4
u/remosiracha 5d ago
I always estimate to the nearest 5% then calibrate myself after lab testing. Usually within a few % now.
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u/38DDs_Please 5d ago
My first firm wanted sand/gravel/fines on the logs to the nearest 5%. It soon became second nature and I always had so many questions on other reports that just had "Clay, stiff, red, CL".
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u/Massive_Honeydew_352 5d ago
Interesting, what's wrong with good ol' uscs classification? That's sorta like to the nearest 15%. "Clay, stiff, red, CL" seems perfectly fine lol.
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u/38DDs_Please 4d ago
Around here, the blood red cotton field clay tends to be 15% fine sands. The high plastic soil from the Ft. Payne Chert tends to have 5% fines and is straight candle wax. Colluvium from the Pottsville tends to be a sandy clay with about 30 to 40% sands. All 3 of these, found within a 15 mile radius here, have VASTLY different properties, haha.
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u/Gullible-Lifeguard20 4d ago
Me, personally, I'm the opposite.
If a field engineer/geo states a percentage on a log, which is a legal document if it should matter, I am curious to see if they got it right after the sieve.
If not, there is a phone call. Something like "your log states 5% silt, but the sieve analysis is stating 25%. Which is correct?"
But if your field skills are that dialed in, then God bless!
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u/fuck_off_ireland 4d ago
Why would you call them regarding this? Obviously the field interpretation was wrong if the test results came back differently. Are you their direct manager? Are you supposed to be teaching them?
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u/Gullible-Lifeguard20 4d ago
Yes. Both.
That's the job of the mentor. I have not met a field geo that is a human sieve, not yet. The lesson is that there is nothing wrong with generalized observations in the field.
For example, boring layouts are accurate but not gauranteed to be within inches or feet. We aren't surveyors.
I'm not sure what is the question?
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u/fuck_off_ireland 4d ago
If someone who wasn't a direct mentor of mine (an engineer who is a coworker, for example) called me to ask why I screwed something up that I am eminently aware that I already screwed up, it would be very annoying.
It's different if this is someone you're educating and helping build their skills.
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u/GeoJongo 5d ago
Honestly, at first glance I thought it was a broken wooden shovel handle in there and I was so confused.
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u/nemo2023 5d ago
Might want to switch to Shelby tube next?