What Rock is this?

[willygoat]

Originally Posted by spaceagent-9

my favorite bill nigh the science guy musical skit is the geology song

Bill Nye the Science Guy - "Rocks Rock Harder" - YouTube

I just showed that video to my science classes last week. I played the music video part with that song over and over. Partly to annoy the kids with my loud singing, but also to engrain the lyrics into their heads so it would stick forever. Mwwwahahahaha!

[codex34]

Soil, clay, gravel, clay, gravel, more gravel, sandstone, mudstone (I hates mudstone), sandstone, dense limestone (1/2 "), sandstone, sand, clay, sand, sandstone, clay.....
From drilling a 20ft well by hand, over 2 years, with the wrong tools, and getting it stuck 12ft down. Had some great help from percy varance and a carbide tipped hole cutter welded to a scaffold tube.
The online video said 2 days to dig a well by hand!!!!!!

Question, why is there sand and clay below the sandstone?

[RdK]

Hi there everybody!

I am honestly suprised that there are so many geologist around here, or ppl with interest in that subject!
I studied Mineralogy and Petrology in Freiburg (Black Forest, Germany) and work now at the geological department at the University of Helsinki, Finland. My job here is rather of geochemical nature: I work with the electron microprobe (EMPA) and do the chemical analyses (in fact, right now!). I have also the SEM (scanning electron microscope) under my supervision, but the vacuum system is broken at the moment.

Here in Finland one can find some very old granites and gneisses and other metamorphic stuff. My favorite rock type here is "Rapakivi granite" and its mystery about the round shaped feldspar crystals..

@ codex34: might be a displacement of the sandstone, or the groundwater alters and weathers the sandstone itself??

Nice thread here!
To finish with an old geologist's joke:

Have a gneiss day!

Rgds,
RdK

[Miles Linnabery]

Dear Swampfox:
In the dawn of time I was an Archaeologist in the early 1970's in the SE New Mexico. I worked on the Atomic waste disposal plant project in south central NM I was the compas man Pre GPS stuff I wore pants with a brass belt buckle no steel in the pockets ect. a USGS crew came out to check on us they needed to find a missing 1/4 corner marker. I was using a Brunton Pocket transet on a monopod All Alumin the USGS guy hand held his Brunton his trophy belt buckle and they made disparaging remarks about the sruffy archaeologists for 1/4 mile until we hit the missing marker within 3" they were 150 yars off. Geologic was sand sand sand. we were too early in the project to see the salt beds.
Trip down memory lane,
MILES

[ultra]

well i'm over looking al mokattam mountain (hill actually) it's a low hill on the southwest of cairo it's not that far from me (1/4 hour drive) it's a hill that was submerged in the past time it looks really good and i think that they found a necropolis inside

thought i should share this

ultra stone

[Swampfox]

Originally Posted by codex34

Question, why is there sand and clay below the sandstone?

You are describing what is probably a "Regressive Sequence". Simple explanation is, when the seas rise or fall, the land at some point is covered with water at differecnt depths, the sea water is loaded with all kind of debris, including "dirt, soils of various sizes. Clay, silt, mud are actually used to indicate particle size. Gravel, sand, clay, silt and mud are dropped out of moving water at different times. Big stuff (gravels) first, medium stuff (sand) next and fine stuff (silts and the like) last.

Without getting any more involved here, what your describing, "sand and clay below the sandstone" is a typical sequence when the ocean recedes (drops). This is a Regressive Sequence".....

The opposite happens (sand and clay above the sandstone) when the ocean advances onto the land. This is a Transgressive sequence..

Don't know if this answers your question.

SFX

[Maltedfalcon]

I live in Mother-Lode Country in California. Lots of quartz, decomposed Granite, clays mica,
natural Asbestos, Mercury and oh yeah gold.
Took Geology in college, We have some very interesting rocks in California
Finding Gold around here is easy, Finding lots of gold around here is tougher...

[codex34]

Thanks for the replies, and I thought buried sand would just compress to sandstone
Will that affect my well? Will the water just leak away now that it can get through the sandstone faster?
Should have mentioned I'm in the UK, in the middle. Ice ages and all that.

We also have some land with an old abandoned gypsum drift mine which has long since wooded over, in the wood are some craters 8-16ft wide and ~4ft deep, first we thought they were sink holes from natural erosion of the gypsum or from the mining, but there aren't any mine works under them, then we thought they were explosion craters from the pom-pom gun that was on the hillside in wwII, but now I'm thinking they are from core sample holes used to find where the gypsum seams were.
100 years of rain will have probably washed the soil/clay into what is left of the sampling holes leaving the craters.
Does that sound feasible? Geology actually creating features in the landscape.

[Swampfox]

Originally Posted by codex34

Thanks for the replies, and I thought buried sand would just compress to sandstone
Will that affect my well? Will the water just leak away now that it can get through the sandstone faster?
Should have mentioned I'm in the UK, in the middle. Ice ages and all that.

We also have some land with an old abandoned gypsum drift mine which has long since wooded over, in the wood are some craters 8-16ft wide and ~4ft deep, first we thought they were sink holes from natural erosion of the gypsum or from the mining, but there aren't any mine works under them, then we thought they were explosion craters from the pom-pom gun that was on the hillside in wwII, but now I'm thinking they are from core sample holes used to find where the gypsum seams were.
100 years of rain will have probably washed the soil/clay into what is left of the sampling holes leaving the craters.
Does that sound feasible? Geology actually creating features in the landscape.

Your water supply is a bit more complex, and I don't have the info or the knowledge to make an educated guess.

And yes, subterranean geology can create "craters" on the landscape....It's often called Karst Topography, and is caused by erosion of underground Limestone/Gypsum deposits, that are dissolved away, leaving open pockets, that later collapse, leaving depressions at the surface.

SFX

[Mechanic]

Well this took a bit longer than I thought. Anyhow, I wish these were clearer but I just shot 'em with my phone. First two are from American Fork canyon showing some great bent layers. Third is from or near Capitol Reef in Southern Utah showing sedimentary layers in three different planes. Fourth and fifth near Moab, above Kane Creek canyon and then looking down at the Colorado river from near the top of Moab Rim trail. I guess I should add that the Capitol Reef shot might be (probably is) wind blown sand and not sediment, strictly speaking.