A poem about March's birthstone, the aquamarine
Rocks In My Head
TThe Jurassic period of the Mesozoic left discoverable rocks in NW Minnesota, known as the Hallock red beds. They are known from drill holes and do not contain fossils. Nearby evaporites in ND and Manitoba suggest that the climate was hot and semi-arid. It is likely that dinosaurs wandered across Minnesota but no remains have been found.
The Jurassic was followed by the Cretaceous when the seas advanced upon North America. The eastern shore of this Cretaceous sea was located in part of MN. Sediment deposited in this sea was mostly siltstone. Conglomerates made up of hematite pebbles are found, which indicates that the hematite must have been formed quite some time before it was weathered and broken up. The entire world most likely experienced warm climate.
Some coal has been found in Minnesota from this time, made up of conifers. It is likely the landscape was swampy. Weathered granites and gneises have left behind kaolinite, which is used in ceramics.
Dinosaur remains in Minnesota may lie under glacial drift. A few cretaceous fossils have been found, including a marine crocodile, sharks teeth, ammonites and snails. Also the variety of plants include flowers, ferns, conifers and deciduous trees.
Here is a video I produced in the virtual world Second Life, about the alternative birthstone for January, the rose quartz.
The Permian Period of the Paleozoic Era, like the earlier periods alas left no rocks behind in Minnesota. But in the western US there are evaporites left when the seas dried up. The interior of the continent was hot and dry, with periodic rains that left mud in low places. There were quite a few reptiles, including finbacks, and considerably fewer amphibians.
As we measure geologic time, the Paleozoic Era was followed by the Mesozoic, the first period of which was the Triassic, occurring 225 to 190 million years ago. Again, Triassic deposits are not found in Minnesota. In the western US there are some, which are red from hematite in an oxidizing atmosphere. The continent slow moved north, so the equator was around by Texas and Florida. Life forms included some dinosaurs, flying reptiles, and small mammals.
In Europe and elsewhere there's a Carboniferous epoch. We in the U.S. divide the Carboniferous into the Mississippian and the Pennsylvanian. Like those of the previous periods, the Pennsylvanian rocks have been eroded away in Minnesota. However, elsewhere the landscape was dominated by swamp, tree ferns, and horsetails. Compaction turned the vegetation into bituminous cole. During this time the Canadian shield was uplifting. The entire continent was tilting westward.
I bought another geology book by the same author as my last purchase. A customer stopped by and gave it a high recommendation. Reviewers complained that much is repeated from the author's other book. I did not find this to be the case. Of course, I am the one who still reads from the book my uncle used at the U of M in the 1950's.
Some day soon I want to go on a rock hunting trip. This can take one of three forms. Either I will go somewhere that has geological features I can photograph. Or somewhere I can pick up samples in the field. Or, somewhere that I can visit a rock shop.
Adventure Publications continues to send me nice gifts. I will handle their products when it's feasible (when I get my road signs back). In the meantime, I can recommend them heartily.
Here is their information.
Adventure Publications, Inc.
820 Cleveland Street South
(8-5 Mon-Thu, 8-4 Fri CST)
Fax: 1-877-374-9016 (toll-free)
In addition to nature books they sell mysteries, cookbooks, Scandinavian humor, children's books, memoirs, poetry, history......
Yes, I'm still reading Minnesota geology, but but I received a complimentary copy, from Adventure Publications, of a stunning paperback titled The Storied Agate: 100 Unique Lake Superior Agates
The Mississippian period in Minnesota is like the two earlier geologic periods. Information is obtained from other areas as there is very little evidence left in the state. Warm shallow seas were probably homes to crinoids (sea lilies). Also, amphibians were likely to have lived near rivers, lakes and other wet areas. Land plants had developed, but not flowering plants.
I have discovered a new aspect of stone collecting that appeals to me very much. Suiseki is the Japanese word for viewing stones. That is, stones presented in their natural state and appreciated as works of art. The practice began in China, where the objects are known as scholars' stones, or Gongshi. The Koreans also have their variation of this art. There is is called seosuk. Western cultures have begun to adopt yet another interpretation of this type of artistic presentation. In Japan, it is often associated with bonsai. In Western culture this art is in its infancy and is still evolving. I hope to contribute to its evolution, now that I have discovered it.
I thought I saw a new store front business in town, and it was a rock shop. Then I thought to myself, I must be mistaken. Nobody in their right mind starts a rock shop. Wow. Did I really say that out loud? I have been fighting this attitude for years, and I've blogged about it and raved about it, and now I've fallen prey to it myself. Yesterday I found an ad in the classified section of the local shopper. I was right. Someone has started a rock shop downtown.
My parents had a rock shop. So did my grandfather. My parents were told in both subtle and not so subtle ways that rocks are a hobby, not a business. As I see it my parents were beaten down by this attitude, persistent and relentless,
until they believed it themselves. I often wonder why the nosy neighbors and others (I don't really remember who it was) couldn't have afforded them the dignity of calllng it a seasonal business. Which it was. Kind of like a resort. They would have felt much better about themselves. Confidence and support might have pushed their enterprize into a more viable arena. My parents were too poor for hobbies and they used every dime for living expenses. Sometimes I could cry.
People try to pull that s*** on me too. When somebody stops in and refers to my hobby I try to set them straight but my first impulse is to say &%#@$%^. And no, this isn't a hobby farm. This is where my grandparents made a living and raised seven kids.
A new rock shop in town! Competition? No, not at all. Just wind in my sails.
I am really bummed out on a trade transaction I made via the forum Dirty Rockhounds. One person was pleased with what I sent and recommended me for another trade. Another person didn't say anything. The third person was "dissapointed", and very sarcastic with me. Her reaction left me dumbfounded.
The last cabochon my 96 year old grandfather made was brown stromatolite which is not flashy but is very interesting. It is an 8 billion year old MN fossil, the earliest life form. Red stromatolites are considered gem quality. I sent her both. My parents and grandparents signed a waiver and went into the now underwater Mary Ellen mine to gather this material. Larvikite, from Norway, also known as Swedish blue pearl, is the stone we used to make both my grandfather’s and mother’s gravestones. A friend who works in mines has been to all 3 larvikite quarries in Norway. 90 percent goes to waste because it has to be cut at just the right angle to take advantage of the “sparkles”. My uncle made it into beautiful belt buckles. I could go on and on. Every stone has a story. Since she was so unhappy I offered twice to send out another box if she would send me her mailing address again. But I got no response. It makes me wonder if my family has been dealing in such worthless crap for over sixty years maybe we shouldn’t have been in business in the first place.
The same as with the Silurian, there is not a lot of evidence of activity from the Devonian period in Minnesota. An exception is a carbonate unit called the Cedar Valley formation in southern Minnsota. The material was deposited by the advance, then the withdrawal, of marine waters. Most of the fossil evidence has been obliterated. Elsewhere in the world there is fossil evidence of bizarre fish types, swamps and forests, and primitive amphibians. It is a fascinating era, for anyone who enjoys reading about the earth's history.
I have received two boxes of rocks and minerals in trade, from contacts I made at Dirty Rockhounds, a site for earth science enthusiasts. Beautiful quartz from SC (Diamond Hill Mine), and others from a collector in WV. Now I have to do a good job of selecting items for my end of the trade :)
According to the geology books, there are no Silurian rocks in Minnesota. Elsewhere there is evidence of primitive plant life, mosses and corals. There may have been vascular plants. But Minnesota was a barren peneplain covered by a very hot sea. The equator passed right through the middle of the state.
I am about to fill in gaps in my rock inventory with a few ordered items: turquoise in forms ranging from good quality cabochons to chalk to beads; carefully chosen fossils including coprolite, and my continuing acquisition of affordable examples of the traditional and alternative birthstones. I opened the tumblers and found that most of the materials have to go back in. Haven't gotten together with the "ladies" to do wirewrap yet. I gathered up all the white rocks for prep and painting during the coming winter...which unfortunately is on its way.