"Ash" identified in borelog 1

[geopat69]

Hi .

My apologies for the seemingly silly query, but I have a borelog that identifies traces of "Ash" at around 2 meters depth. The log does not state the strata is fill.

In terms of understanding the term..."Ash", is this meant to be a soil geological term , OR, is it literally meaning ash from fire?

With my limited understanding on geology and soil, I find it hard to understand how ash (from fire) ends up 2m under ground...its left me wondering if "Ash" means something more geological?

Appreciate any advice.

FYI location is Brisbane, Australia.

Regards
Geopat

 

[fattdad]

volcanic ash?

Flyash - i.e., fill from nearby coal power plant? (These coal-combustion products do find their way into civil improvements.)

Random incinerator ash - i.e., also as fill, but unlikely much fitness?

Yeah, not a good log if the nature of the stratum is not considered.

f-d

ípapß gordo ainÆt no madre flaca!

 

[fel3]

At 2 m down, could this be evidence of an ancient volcanic eruption? I don't know what, if any, ancient volcanoes are in the vicinity, but Indonesia is not that far as the ash flies and they have some of the biggest and most temperamental volcanoes on the planet.

============
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[Ron]

Just because you hear hoofbeats, don't look for Zebras......Likely fill with some common ash from either past forest fire or dumped ash.

 

[geopat69]

Hi guys. Thanks for the response. Appreciate it.

Fattdad: When you say the "not a good log because the nature of the stratum is not considered", are you meaning that it's because the geotech engineer should have stated if it was fill or not (or given some more info?? All it says at 2m down is silty clay (stiff) with traces of Ash.

Fel3 and Ron: if it is NOT fill, is it possible that a past bush fire (or ash from volcanoe) could have lasted so long?

 

[dik]

Any chance it is designated as Organic?... else it could be volcanic ash... they should have noted a distinction.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[oldestguy]

Could be an ash dumped. I had a job nce where one sample was thought to be a natural deposit. However the job insector identified it as coal ash, meaning the who9le site was underlain by dumped coal ash, not discovered as ssh in the test borings. That inspector saved a lot of grief. Incidentally he is my son. A fuss budget.

 

[geopat69]

Hi all. Its not coal ash. In any case its only in traces. Also, the bore log makes no memtion if its organic. Not sure how they'd be able to tell if it was inorganic anyway. It is a bush land greenfield site with no prior useage history. So i am leaning to a past (ie very long time ago bushfire). Thats perhaps burnt tree stump to that level.

But i guess the point of my query is if "ash" means something in geological sense. ?

OR if burnt tree stump ashes can last for decades or 1000s of years...in the ground and still be indentifieable when in a bore?

 

[fattdad]

A visual classification, "Silty Clay" is meaningless to me. I use ASTM D2488 and it's not a choice. Silty clay requires a laboratory test and is quite rare. When I see it on a visual log, I just figure the logger just didn't know what it was. Clearly then, "Ash" is without context.

f-d

ípapß gordo ainÆt no madre flaca!

 

[cvg]

volcanic ash is not like fire ash. Ash from an eruption is small pieces of rock or glass. it has a much different shape than ash from fires and is very dense. it should be easy to identify by microscopic visual analysis or by calculating the density if a sample was obtained