I need a beach geologist!

[Annie M.]

Just wondering if anyone can provide me with some information about a sedimentary layer I found at the beach the other day.

The shore at this spot is primarily sandstone that is packed with shell fossils (huge abalone, snail spirals, clams, strange leaves) so I assume that at one time this was the sea bed... this fossil layer is about 20 feet thick and forms a cliff above sea level. The layer that I am interested in is below the sandstone and appears as a black line in the strata... in a few small exposed areas in the intertidal zone this layer appears to be pure carbon (not shale)... jet black with a 'alligator texture to the surface.. I chipped a piece out and it is extremely light. I think it is charcoal... it will make a mark on a piece of paper... it also appears to have a very tight 'grain' when I look at it under a magnifying glass.

I am on the west coast of Vancouver Island and I am very curious about the origin of this 'charcoal' layer and what it actually 'is'. Any insight is appreciated.

Thanks... Annie

[redrockcoulee]

There is a web site that I cannot think of its name, but it is the BC government and there are geological maps on it. But the best would be to contact the geology or geography departments at U of Vic and if you can give the precise location they will be able to tell you the actual formation name so you will find out not only the type of rock but the age of it as well

[Annie M.]

Thanks redrock... long weekend... lights out at U vic.

I never give out the exact location of anything I find ever!! Down the coast at Muir Creek the fossil cliffs have been chewed to bits by the people with their sharp shiny hammers.

I never revealed the location of the petroglyph I found either... although the government does keep a 'secret list' of significant anthropological sites that will never be revealed to the public... mine wasn't on it and will never be. Sounds paranoid I know but it is amazing what some people will try to drag home from the beach.

[Ole Tjugen]

That sounds like coal - at least to this petroleum geologist. :)

[Bryan Lemasters]

Annie,

A local government geological survey office would be able to answer you question. Take a sample of it to show them. This vein may be very localized and not show up on a map, though. While it could be the carboniferous remains of a small bog later covered by other strata, it sounds more like it could also be the remains of a tar pit or oil seep. In Ritchie County, West Virginia (a long way from Vancouver Island, I know) there was an oil seep that woked it's way up through fissures in the surrounding rock strata along an anticline and over the eons solidified into what appeared to be coal (and was mined as such). However, when heated or burned, this "coal" would melt and drip. Try breaking off a piece and lighting it. Will it burn? Does it appear to soften or melt? Sounds interesting. Good luck.

Bryan

[J D Clark]

My wife, a geologist who got her doctorate in sedimentary geology, also supports Ole's answer that it's coal.

John Clark
www.johndclark.com

[David Vickery]

http://www.llbc.leg.bc.ca/public/PubDocs/bcdocs/96990/1987/441-450-bickford.pdf

This is a link to an assessment of the coal on Vancouver Island. Although they mainly address the eastern side of the island--I didn't read along far enough to see if they mention the western side of the island--it isn't unlikely that the same formations would extend across the island.

[Annie M.]

It glows! I can get it to glow red by a candle flame... looks like it is coal... smells organic when it smoulders... wonder if I can grind this down and do some kind of carbon printing with it... now if only I could find a vein of platinum to print with!

Thanks everyone... a

[Ole Tjugen]

"Coal" is a very wide classification, and in "proper" classification we use a lot of different terms for various different properties.

Finding thin layers of coal in sandstones is not uncommon, and in oil drilling it is one of the most common "problem zones".

[Ole Tjugen]

By the way: http://web.viu.ca/earle/mal-cut/geology-of-vancouver-island.ppt is a good summary.

Just detailed enough that I can guess where your beach is. :)

[jim kitchen]

Dear Annie,

The current mountains along the British Columbia coastline are believed to be formed by a larger island that existed several eons ago off the British Columbia coast, where this large island subducted under the North American Plate, creating the mountains we enjoy from Alaska to approximately the Washington State and British Columbia border today. The Canadian mountains are believed to be formed completely, and very differently geologically, compared to the mountain chains found along the western side of the United States because of this presumed former large island off the British Columbia coastline, compared to volcanic geological events south of the border.

Therefore, geological layers would more than likely be exposed from previous deposits of oceanic sediments, and previous carboniferous deposits...

As a side note, the Canadian portion of the Rocky Mountains is also believed to be presented more than one once, during their cyclical geological history prior to the large island crashing into the North American Plate. Portions of Western Canada, along the entire length of the Canadian Rockies leeward side, have salt layers that are four hundred to eight hundred metres thick, and they are found at depths greater than 1000 metres below the current surface. These salt layers can be possibly explained by trapped evaporating oceans, caused by continuous plate tectonic action along the west coast, where plate tectonics created the rising mountains trapping the saltwater and allowing the evaporation event to begin, geological time eroded the previous mountain sets allowing each salt layer to be covered with quietly deposited fine sedimentary shale like material, therefore separating the deposited salt layers.

Please forgive my vague overview and explanation, but I am remembering faded text from my university days where I studied geology, coastal geomorphology, and glaciology as a distraction from my Architectural studies. Then again, maybe my memory has faded... :)

jim k

[Nathan Potter]

Ole is probably on the right track with a form of coal. Does it smell of sulfur when you heat it? How thick is the deposit? If it is very thin and slightly lighter than coal it could be a compressed layer of volcanic ash.

Nate Potter, Austin TX.

[Ole Tjugen]

I suspect it's a thin layer in the tertiary sediments; thus not very hard or very sulfurous. It would most likely be lighter than "ordinary" older coal.

[Annie M.]

The layer is only a few inches thick and smells slightly sweet and organic... that may perhaps be because it is usually beneath the sea.

Anyway I did find a mention of 'sea coal' used as a pigment in the late 1600's in the Pigment Conpendium so I am going to give it a try for an image of that place... I can add it to my collection of things where the photograph is made using the thing itself... so far this has been trees and plants... this will be my first landscape in the series if it works.

[Brian Vuillemenot]

Sounds like lignite to me- an earlier stage of coal than the commercially mined varieties of bituminous and anthracite, and much less dense.

[walter23]

Old thread I know (I was looking through Annie's posts to see if there were any posted images), but I found some really interesting stuff on the east coast of the island this week - a bunch of hardened lava flow material (not sure if pumice is the correct type of rock - you can see the bubbles and rivulet surfaces on this stuff! Very cool)... and also a mid-sized rock containing what looks like real gold, perhaps intermixed with a bit of pyrite (these little veins are *very* yellow and amorphous, now the sort of brown / cubic look of pyrite).

On the subject of rock hounds and fossil collectors - I'm got mixed opinions. It ruins the aesthetic of an area, so I don't really like it, but on the bright side, intrusions with a rock pick can only really scratch the surface and in ten thousand years when we're all dead and gone new layers of fossils will erode out and become exposed.... so in the long term, no harm done, by this kind of casual surface stuff anyway. Open pit mines and stuff might be a different issue, those will probably be around for a very long time!

[Annie M.]

Checking me out to see if I am good enough to be in the boy's club are ya! click on my profile and you will see the only image I have on this site... a sad little scan but my first.

[walter23]

Checking me out to see if I am good enough to be in the boy's club are ya! click on my profile and you will see the only image I have on this site... a sad little scan but my first.

Haha, there's no judge or jury in this group ;)

Just curiosity!

[PenGun]

You can find veins of hard clay too. Some of it is nearly black.

[sanking]

I assume that folks on Vancouver already know this, but if anyone does not coal mining was a very big industry around Nanaimo from the mid-19th century until recent times. Nanaimo is on the southeast coast of the island, about 30 miles west of Vancouver, separated by the Strait of Georgia.

There was also some coal mining in the past on Gabriola Island, just to the east of Nanaimo in the Strait of Georgia. I have often seen sedimentary rock layers on Gabriola that looked like coal to me.

Sandy King

[PenGun]

There are still miner's houses and some coal works up near Cumberland. Union Bay has some wonderful old buildings and I think I'll need to take the 45 up there this summer and tramp around a bit.

[Annie M.]

You know another thing that is splotched on the rocks here is Weston beach tar...

[Martin Courtenay-Blake]

Could well be oil shale, especially as tar is found in the same area. If you put a piece in a container and heat it it will release crude oil if it oil shale. Oil shale, coal and lignite will all burn if subjected to direct heat. If it doesn't then it is most likely a normal dark shale which often contains fossiliferous remains which may be responsible for the organic smell. It is common for shales to be found in thin beds in other sedimentary deposits. It is formed by the gradual compression of clays in esturine conditions. As the overlaying strata are indicative of shallow marine conditions it may point to a river estuary eventually flooded by rising sea waters.

Martin

[Hollis]

What does it taste like? Taste is one sense that often gets overlooked in these sorts of things.

[Annie M.]

It tastes like a hot summer road.