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SOAPSTONE! Book on its archaeology and history!
Book: The Stones of Nidaros Cathedral
Book: QuarryScapes
Author Archives: Per Storemyr
Soapstone in the Far South of Norway (II): The Østre Vimme Multiperiod Quarry With Very Soft Soapstone
Østre Vimme is another of the several old soapstone quarries in the Aust-Agder region of Southern Norway. It was worked in the Iron Age for «standard» vessels, but it has at least three production phases, for which there may be a specific reason: Parts of the quarry feature very talc-rich and soft soapstone, implying that the stone was also easy to carve for small items like spindle whorls, sinkers and lamps. Hence, it would have been a valuable resource for a long time. Softness may be the result of a special geology. Dutch geologists have suggested that this is a deposit not derived from alteration of ultramafic rocks, which is by far most common mode of formation in Norway. Rather, it may derive from alteration of dolomitic limestone. There is only on other known soapstone deposit in Norway with such an origin. Here’s an account of this exciting quarry, also including a discussion of whether soapstone vessels from the quarry were exported to Denmark in the 9th century CE. Continue reading
Soapstone in the Far South of Norway (I): The Sparsås Iron Age Quarry
The region of Aust-Agder in Southern Norway hosts a range of Iron Age soapstone vessel quarries. One of them, the Sparsås quarry in Froland, is exceptionally well-preserved and one of the most “classic” quarries I have ever visited in Norway. With unfinished vessel blanks still attached to the quarry faces and a highly organised layout of the spoil heaps, it once must have been worked in an efficient way, providing vessels and other items for regional use and, quite probably, for export to Denmark and beyond. Here’s an account of the research history, geology and layout of the quarry. A hypothesis is also offered: This was a short-lived quarry, operated for a generation or so within the 9th or 10th century CE. Continue reading
Tafoni-forvitring i larvikitt på Rakke ved Stavern
Tidligere i høst prøvde jeg å finne tafoni i larvikitt på svabergene ved Rakke utenfor Stavern. Så vidt jeg vet, er ikke tafoni noe vanlig fenomen i den grove larvikitten, men så var jeg heldig og kom over et lite felt rett i vannkanten ut mot havet, der larvikitten er bygd opp med svært tydelig, magmatisk lagdeling. I de litt mer finkornede lagene med mørkere mineraler trådte tafonien frem, som rekker med større og mindre hull. Continue reading
Posted in Geomorphology, Norway, tafoni
Tagged grusforvitring, larvikitt, magmatisk lagning, Rakke, Stavern, tafoni, tafoni weathering, tafoni-forvitring
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Bioerosion of shells on the beach – and in old Norwegian lime mortars
Looking closely at shells on the beach, you will find that most have smaller and larger holes, tunnels and “galleries” made by boring organisms. This is bioerosion, a powerful part of the process that makes shells break down and eventually become part of a shell sand deposit. Along the coast of Norway, such deposits were sometimes dug for aggregate to make lime mortars for building medieval churches. And bioerosion of shell fragments in the mortars can still be seen under the microscope. It may aid the understanding of how the mortars were made. Continue reading
Posted in Archaeology, lime burning, Marble, Weathering history
Tagged bioerosion, kalk, lime, lime mortar, lime mortar microscopy, Moster gamle kirke, Norway, Sakshaug gamle kirke, sea shell
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Madam Jørgensens 230 år gamle feltspatgruve i Narestø
Det var en kvinne som startet utvinning av kvarts og feltspat i Norge. Omkring 1790 rodde madam Jørgensen langs Sørlandskysten for å finne feltspat hun hadde planer om å selge som råstoff til kongens porselensfabrikk i København. Ved Narestø på Flosta fant hun det hun lette etter. Det ble starten på et mineraleventyr. Jeg skrev om eventyret for 10 år siden. I dag fikk jeg endelig ta Norges eldste feltspatgruve i øyesyn. En velbevart gruve som var i drift helt til 1920-tallet. Continue reading
Posted in Archaeology, Norway, Old mines
Tagged feltspat, Flosta, gruve, kvarts, Madam Jørgensen, Narestø, Narestø feltspatgruve, pegmatitt
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Tafoni blant jettegrytene på Kvaknes (Kilsund)
Kvaknes ved Kilsund på Tverdalsøy i Arendal kommune er kjent for sine mange jettegryter. Siden dette er en odde helt ut mot Skagerrak, burde det potensielt være et bra sted for tafoni-forvitring. Mye tafoni er det imidlertid ikke her, men det lille som finnes er eksemplarisk fordelt på de “svakere” bergartene – på mørk amfibolitt og i skifrige soner. Slik fordeling er klassisk for tafoni-forekomstene på Sørlandskysten. Continue reading
Posted in Geomorphology, Norway, tafoni, Weathering history
Tagged amfibolitt, Arendal, Flosta, forvitring, gneis, KIlsund, Kvaknes, landheving, Norge, Raet nasjonalpark, salt weathering, saltforvitring, Sørlandet, Sildodden, tafoni, tafoni weathering, tafoni-forvitring, Tromøy, weathering
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Impressions of limestone bioerosion on the Croatian island of Mljet
As the final destination of our family’s road trip through Europe this summer, the Croatian island of Mljet offered a beginner’s crash course on bioerosion of limestone. My experience in weathering has mostly been connected to abiotic phenomena such as salt and frost weathering, so it was fascinating to observe the bizarre forms made by living organisms, especially in the littoral zone of the rocky coast. Particularly interesting is the boring into the limestone by bivalves, limpets, barnacles and several other organisms. Continue reading
Posted in Geomorphology
Tagged Adriatic Sea, bioerosion, biokarst, boring organisms, coastal bioerosion, Croatia, Geomorphology, karst, limestone, Mljet
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Tafoni-forvitring i skogsterreng på Flosta
Grotter og hellere dannet av brenninger og bølgeslag er ikke et vanlig syn på Sørlandet. Men under en vandring i vårskogen på Flosta kom jeg forleden over en lav heller, ganske sikkert dannet av brenninger da havet sto 20-30 m høyere enn i dag. Det fine med helleren er at den er full av tafoni i taket. Og også i omgivelsene er det mengder med tafoni – alt i en 600 m lang og nesten 30 m høy brattkant med metagabbro og migmatitt, og alt 25-30 m over havet. Hvorfor finner vi tafoni akkurat her? Continue reading
Posted in tafoni, Weathering history
Tagged Arendal, Flosta, forvitring, gabbro, gneis, landheving, migmatitt, Norge, Raet nasjonalpark, salt weathering, saltforvitring, Sørlandet, tafoni, tafoni weathering, tafoni-forvitring, weathering
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Grunnmuren til Fastings Minde i Bergen: Etter 5 år står tradisjonskalken fortsatt godt!
Den store grunnmuren til 1700-tallsbygningen Fastings Minde i Bergen ble i 2020 restaurert med tradisjonskalk. Arbeidet ble gjort under et større kurs i bruk av “hjemmebrent” kalk fra ovnene i Hyllestad. I dag, 5 år etter, står den værutsatte muren … Continue reading
Posted in lime burning, Marble, Monument conservation, Norway
Tagged Bergen, Fastings Minde, Hyllestadkalk, hyllestadmarmor, kalk, kalkbrenning, kalkhvitting, kalkmørtel, kalkslemming, kurs, lime, lime burning, lime mortar, Osterøykalk, restaurering, sand, tradisjonskalk
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Per Storemyr Geoarchaeology & Conservation 