Question: Is that pyrite crystals in this piece of oil shale? I picked it up on the beach on my last trip. Or is it some strange fossil? Whatever it is, why/how/when do they form like this in the shale?

Yesterday I was on a fieldtrip to the south eastern regions of Scania (which is the most southern Province of Sweden, where I live). It took me among many things to a very small village by the ocean called Simrislund. This place is interesting geological-wise since its one of few places where Cambrian quartzite is very abundat at the surface as bedrock. Most of the bedrock is smooth and grinded flat by the last iceage. Sprinkled all over the landscape and the shoreline is oilshale since this used to cover the cambrian rock but nowdays is eroded away. Further inland the shale is still intact as bedrock. The shale is also full of fossils like brachiopods and trilobites.

One other interesting aspect of the Cambrian quartzite is the human impact on it. At Simrislund there are many rocks with carvings on it from the Scandinavian bronzeage over 3000 years ago. This makes this place both culturally and geologically worth a visit.

In my collection of “things and stuff” I got one really nice object that usually makes people envious. It’s a shaft hole axe from Uppland in Sweden. It was my grandfather who in his youth found it on a field. The archaeological dating sets this axe to the middle or late Neolithic. Around 3000 BC perhaps. But I’m not sure on that, it’s been a while since I took archaeology and the making of shaft hole axes streches some time.

Geology-wise this axe is made of, what I think at least, some form of ordinary diabase. The weight, the archaeological practise of using diabase, it all tells me this at least. There’s no volcanoes in or near Uppland (which basically is mostly old igneous bedrock, granites at about 1800 Ma), so I dont think its basalt, but rather diabase. It could be imported/transported of course. But theres a lot of shaft hole axes found in Uppland so I dont think so.

At first, the axe was all nice and shiny black in colour, with some hints of olivine green even. But then I decided to wash it and under a thick layer of like 70 years of handling and showing to people (sounds better than 70 years of deposited human dirts and fats) and that revealed a more grayish dull stone with a hint of green tones. Theres also some redish spots that came out from under the filth which looks like rust almost. I’m not so sure any more of what this stone is made of in detail since no crystalline structure is visible because of the grinding and smoothing of the axe. Any suggestions? My guess is diabase and that the small cracks and holes are the result of erosion of more fragile plagioclase in a resistant matrix of augite and olivine.

Anyhow, depending how you look at it, its an 5000 year old axe or a 1800 million year old pice of rock. And its all mine, my sweet precious shaft hole axe… 

I’ve been saving this rock for a later post. But complications have made it impossible for me to examine the rock up close any time soon. All I have are these older photos below. So I can just write about it now I guess, it wont matter if I wait any longer.

It’s (supposedly) not magnetic (that rules out iron slag right?). It (supposedly) weighs about 1-2 kilos. Its about 15x10x10 cm in size. (reduced size on the photos)

I sent the photos to an geology expert a couple of years ago, before studying geology myself in the hopes of helping my (now sadly enough dead) friend in helping to identify it.

The expert just replied shortly and claimed that it “most definitely was a conglomerate”.

Im no expert, just a first year student. An amateur. But this doesn’t look like any conglomerate that I know of. Where are the pieces of rocks and granules? Shouldn’t there be at least one lousy piece of granule visible if the craters are the sockets of rocks? Are they really all loosened and gone? Doesnt sound very plaucible to me. And when I replied to the experts answer with a follow up queastion and asked how this could be a conglomerate without any visible captured parts, his stuck up pride probably got offended and he just got bored with me and didnt answer at all. I almost lost all faith in geologists that time. What an idiot. Esteemed professor emeritus of Lund university and all. Well, he didnt make that far in the academical world on being friendly to the taxpayers who payed him and his research (Publically funded universities in Sweden you know). Well enough about him.

In my, very unprofessional opinion, this looks much more like a meteorite. But according to the expert, that wasnt even an option. I really never understood why.

I know that meteorites of course are less likely to be found in comparison to just about any type of rock. I’m not stupid on that part. But I can’t get over the fact that it looks like one much more than it looks like a conglomerate.  

The rock also comes with a story (from my dead friend) that his father actually saw “a falling star” and went looking in the direction of where it seemed to have fell. Some miles away he found burned grass and this piece of rock between some cliffs at the west coast of Sweden. Around 1920 I think he said this all took place.

What does my readers say? Conglomerate? Meteorite? Iron slag? Flint? Or something else? What can you make of it just by looking at these photos (that’s all I have, its impossible for me to examine the rock itself or take better photos any time soon). Im all ears.

Got a new camera. Nothing fancy, a "Canon digital Ixus 950 is". But it had a nice macro-function so i took som new photos just for fun.

Picture below is a garnet crystal inside of a amfibolitic rock. Hornblende to be precise. Picked it up on an excursion.

Picture below is of a olivine crystal (or a couple of them of course) inside a basalt rock from a small dead "vulcano" in the middle of Scania. Age about 145 Ma. Picked it up on an excursion.

Picture below is of an ordinary sandstone heavily oxidized with iron found in an Jurassic-Trias-deposit of sand. Its composed of several layers of differently oxidized and dense sediments. Looks more strange than it is. 

The picture below is not totaly geological but still quite nice. A piece of iron slag from Uppåkra (Uppakra) Iron age settlement outside Lund (roughly 700 AD perhaps). Since I started my career with archaeology I also have some archaeological things in my possesions. Some of them I actually found myself on field training exercises like this slag and the piece of pottery below.

The picture below is of a piece of Iron age pottery from the same settlement/village.  

Perhaps I should share some general geological information about my part of the world.

Sweden and the Scandinavian peninsula was formed geologically from the continent of ”Baltica” which today is called the Baltic Shield or the Fennoscandian Shield. It consists of today’s Sweden, Finland, Norway, Northwestern Russia and parts of the Baltic Sea (not Denmark geologically). The Baltic Shield has a maximum age of about 3.1 Ga, but most parts of Sweden is formed on 2-1.5 Ga old granits and gneiss. In general its older to the north east than to the south west. Many parts of today’s mainland of the south east, like Skåne (Scania), the province where I live, is younger and formed of sedimentary deposits. But the Baltic shield is still below the sediments even here, some 2-3 kilometers and can be seen at some horst formations, especially along the Tornqvist zone. Scandinavia has a quite a variation of landscapes, both because of the differences in geology, but mostly due to the geographic distances. Some parts of the north have a arctic climate almost (Like Canada or Alaska). And here in the south there is a temperate climate. Probably the same as you might find around Boston or New York. The same temperate climate goes for Denmark, wich geologically consists only of sedimentary rocks and therefore technically isn’t a part of the Baltic Shield. Picture below of Baltic Shield.

The mountain range of Sweden and Norway is called the Scandinavian Mountains (“Skanderna” in swe.). It’s actually related to the Appalachian mountains since both belong to the Caledonian orogeny. Back in the days (450 Ma) they were connected before the Atlantic Ocean was formed. Picture below of Scandinavian mountains.

Picture below is Padjelanta national reserve in the north of Sweden. Typical view of the mountain landscape during summer.

Picture below is of Sarek National reserve in the north of Sweden. 

Pictures below shows parts of the Norwegian costal landscapes with their Fjords. Insanely beautiful if you ask me. Perhaps some of the most beautiful types of landscapes in the world. One could easily make an entire blog about the Norwegian fjords.

Today, in the lovely spring weather we have here in the south of Sweden, I took a small trip out to the nature reserve called Billebjer just outside my town of Lund. It’s part of the horst that is called Rommeleaasen, a horst that is part of a greater geological system called Tornqvist zone. Basically the Tornqvist zone is a lot of ancient faults stretching from the Black Sea to somewhere outside Scotland. This zone begun to form some 300 million years ago and the horsts was raised some 60 million years ago.

Most of the rocks are difficult to identify by visual means since the bedrock is covered with growth and heavily cracked and eroded. And fresh surfaces of bedrock only reveal a diffuse rusty rock. But looking at the bedrock up close revealed more typical traits of a granite. And small traces of a metamorphic process could also be seen. But I was far from sure so I had to cheat and look it up at the webpage of the Swedish geological survey. According to them it’s a Orthogneiss. But Im not completely convinced and some pages on the internet talk about a granite-gneiss. That is, a only slightly metamorfed granite. But other sources talked about an Amphibolite rock that also is common in this horst. Well, my guess is a very iron rich granite-gneiss perhaps. Its so full of this "rust" that its almost impossible to see what it is. It almost looks like a sedimentary rock at a distance. But that much I know, it isnt.

Igneous bedrocks are not the dominate bedrock in the very south of Sweden (where I live). Most of the bedrock here is sedimentary and the metamorfed or igneous rocks are hidden deep below or only revealed through horsts. The Billebjer formation is one of few spots where I can look at the bedrock in close vicinity of Lund. North of the Tornqvist zone the igneous bedrock becomes more and more common. And basically 90% av the Swedish topside bedrock is metamorfic or igneous. The province of Scania (Skåne) where I live and the island of Gotland are the exceptions and especially here in Scania you can find all sorts of bedrock. From 2 billion year old igneous rocks to tetriary sedimentary deposits.

I have two pieces of rock which I cannot identify for sure since Im quite new at geology. I would like your opinions of them and what you know or think. I have no instruments at home so the photos is basically what you get. If you aren’t sure, an educated guess is better than nothing.

Rock A

Found on the island of Gotland (as you now know have a primarily Silurian lime stone bedrock). Def. sedimentary. Perhaps a conglomerate of some sort? White circular or oval granules surrounded by grey filling. The white filling however looks a bit precipitated almost. And the white granules seems to erode more quicker than the surrounding area. Also a couple of charcoal-looking black crystals (but a lot harder than ordinary coal. Perhaps a hornblende?) embed inside some of the white granules. No certain trace of any distinct macro fossils. Low density/weight.

Rock B

A rock with heavy density and large milkywhite plagioclase-looking crystals (they look more transparent on the closeup picture than in reality so ignore the transparent effect on the close up) embedded in a black igneous rock. No traces of quartz what I can see. There are also a few random red granules or "holes". Found on the Swedish mainland so it could very well have come from anywhere due to the ice age.

Gotland is the largest island in Sweden. It’s a great place to visit for many reasons, not the least for its history and geology.

The islands largest town Visby belonged to the German Hanseatic-league during the middle ages (it was a community of traders that controlled most of northern Europe at this time). A town of great wealth back then. But after the middle ages the economy fell and that’s basically the reason that the town today is such a great place to visit if you are historically interested, since so much is preserved and not destroyed. Nothing or nobody came after and tore away the medieval town.

For this reason Visby is a haven for people who likes medieval activities. They even have a huge medieval festival and market in early August with everything you would expect to find at such an event. If you are planning a trip to Sweden, then try to fit in a trip to Gotland, you won’t regret it. The picture below shows a medieval knight standing outside the medieval town wall of Visby.

Geology vise the island of Gotland is just one big rock of Silurian limestone, primarily reef built limestone that was deposited at a time when Gotland was a giant reef near the equator. There’s not much other types of bedrock there. But who cares since Gotland is a haven of Silurian fossils.

One basically just has to pick up a rock and it will contain fossils from the Silurian period. I collected some fossils on my week long vacation trip there in August of 2007. I primarily found Anthozoa (corals) of different types. Here are three examples of the several pounds which I dragged with me home after the vacation.

The picture below shows four samples of Rugosa coral.

The picture below shows a sample of Favosites, a tabulate coral.

The picture below shows a sample of Heliosites or “Sun coral”, also a tabulate coral.

The pictures below show the strange formation knows as Rauks. They are the result of erosion that has exposed more harder reef sediments when the more brittle limestone around eroded away. It’s a quite recent event that started after the ice receded from this area after the last ice age (12000 Bp). These rauks are found in great numbers around the coast of Gotland. And yes, they are packed with fossils.

The picture below shows a closeup of the bedrock. As you can se its full of visible macro fossils.

During the excursion yesterday we visited a place called “the priests bathtub” (Swe. “prästens badkar”).  It’s a rocky sandstone beach in the village of of Vik on the east coast of the province of Skåne (Scania) in Sweden. The sandstone is called “Hardeberga sandstone” (or Hardeberga quartzite since most parts of it actually has metamorphosed to some degree). I believe its the oldest forms of sedimentary rocks we have in Sweden.

The sandstone was deposited in the early Cambrian (542-513 Ma). That means that the ocean that slowly erodes the sandstone today isn’t the same ocean as the ocean that the sandstone once was a white beach at. Literally speaking, since the continents have migrated a lot since then. The sandstone was formed on a great depth and pressure and the rocks that were above it have eroded away. Perhaps a mile or two of rocks have eroded for this sandstone to reveal itself. It becomes quite a mental challenge trying to depict this in front of you. First the deposit of the sand, then the rise of new layers of sediments above this, mile after mile, pushing the sand lower and lower and then finally the rise of it all due to tectonic movements, but mostly, actually because of erosion. Quite a journey.  The early Cambrian was another world with another climate, and hardly any breathable air to breathe. No life on land at all, just in the oceans. Hundreds of millions of years before the first dinosaurs even. And now over 500 million years later, half a billion years, it’s a beach, once more.

And inside the rocks, the trace fossils of ancient life that actually survived the journey.

Picture below. Beach overview.

Picture Below. Example of stratigraphy. 

Picture below. Trace fossils. Tracks of "worms". 

Picture below. Sample of Hardeberga Sandstone with trace fossils. You can see small "tubes" that are filled with other sedimentary material. The oldest fossils in my collection. Early Cambrian.