{
  "@type": "Article",
  "type": "knowledge",
  "title": "The limestone beneath Gotland: a geological introduction to the island's hemp ground",
  "url": "https://helsama.se/en/kunskap/kalkstenen-under-gotland/",
  "language": "en",
  "summary": "Gotland's limestone bedrock is 419–428 million years old and shapes the island's soils. A personal account of why geology matters for the hemp.",
  "answer": "Continue reading:",
  "author": {
    "name": "Daniel Johansson",
    "url": "https://helsama.se/forfattare/daniel",
    "jobTitle": "Grundare, Helsama OÜ"
  },
  "publisher": {
    "name": "Helsama OÜ",
    "url": "https://helsama.se"
  },
  "published_date": "2026-05-13T12:39:12.351199+00:00",
  "modified_date": "2026-07-27T08:42:23.049364+00:00",
  "category": "kvalitet",
  "image": "https://rajqtzgkxymypdinmmgj.supabase.co/storage/v1/object/public/knowledge-images/kalkstenen-under-gotland%2Fhero-ammonit-kalksten.jpg",
  "video": "https://youtu.be/TuECI1nXDAQ",
  "markdown_url": "https://helsama.se/en/kunskap/kalkstenen-under-gotland.md",
  "faq": [],
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  "content_markdown": "I found my first crystal on Gotland when I was five years old. It is a long story for another time, but the experience taught me that you can live your dreams.\n\nThere is something about Gotland that is hard to explain unless you have been there. A deeper calm across the island. A different light. The local food tastes different. The water tastes different. Most things are simply — better. And as I have come to understand over the years, it is not just a feeling.\n\nIt is the limestone.\n\nOn Gotland you stand on an unusual foundation. It is limestone — formed in a tropical coral reef around 419 to 428 million years ago, when the area that is today the island lay south of the equator at low southern latitudes. The soil that lies on top of this bedrock is, to a large extent, the result of the limestone's weathering. It is the conditions in that soil that make Gotland distinctive — not just for hemp, but for most of what grows there.\n\nHelsama processes hemp from Gotland. This article is not about what processing entails. It is about what lies beneath the field, and why geology matters.\n\n## What limestone is\n\nLimestone is a sedimentary rock composed of more than 80 percent calcium carbonate. It typically forms on the seafloor, often from accumulated shells and skeletons of marine organisms — corals, brachiopods, crinoids. Gotland's limestone dates from the Silurian, a period in Earth's history between roughly 443 and 419 million years ago. At that time, the landmass that is today the island was part of a tropical marine environment of coral reefs and limestone platforms, south of the equator.\n\nWhen you break open a piece of Gotland limestone you can still see traces of that tropical sea: coralline structures, fossils of snails and brachiopods. The rock has preserved the imprint of its origin.\n\n*Geological map of the Silurian formations of Gotland (Calner, Jeppsson & Munnecke, 2004).*\n\nGeologically, Gotland's bedrock is divided into a series of limestone, marl and shale units — from the Lower Visby Formation (the oldest exposed layers, around 428 million years) to the Sundre Formation (the youngest, around 419 million years) — but the entire island rests on the same Silurian limestone bed. The Geological Survey of Sweden (SGU) has mapped Gotland's bedrock in detail since the 1920s in the so-called Hede series (Hede 1921, 1925, 1929, 1940). The modern stratigraphic overview is compiled in Calner, Jeppsson & Munnecke (2004), \"The Silurian of Gotland — Part I\", published in Erlanger geologische Abhandlungen Sonderband 5.\n\n## How the limestone has shaped Gotland's soils\n\nRock breaks down. It is slow work — frost, water, plant roots, chemical reactions with carbon dioxide in the rain — but over millions of years it has turned limestone into topsoil. On Gotland this means that the soil you encounter on most fields is not primarily clay or sandy moraine, but calcareous loam with direct influence from the limestone beneath.\n\nThree consequences for growers:\n\n- **High pH.** Calcium carbonate reacts with water in the ground and raises the soil's pH. Gotland fields generally sit at neutral to mildly alkaline levels — distinct from the often more acidic soils of the Swedish mainland. This is a consequence of the underlying limestone bedrock rather than liming or other soil amendment.\n\n- **Excellent drainage.** Limestone is a fractured rock. Water runs down into the cracks instead of standing on the surface. This means Gotland fields rarely become waterlogged after rain — water is led away before the root system suffers.\n\n- **Limited capacity to retain certain nutrients.** This is not purely an advantage. The high pH binds phosphorus and several trace elements, making them less available to the plant. As a result, Gotland growers tend to work more with organic fertiliser than with conventional mineral fertiliser.\n\n## What this means for the hemp plant\n\n*Cannabis sativa* is a plant that, on its own, prefers slightly alkaline to neutral soil and good drainage. Conditions on Gotland therefore align well with what the plant botanically thrives in.\n\n\\n\n\nFor a deeper exploration of what actually defines premium-quality Swedish hemp, see our [Knowledge Hub](/en/kunskap/premium-cbd-sverige).\n\nThis is an agronomic observation, not a claim about the product. When a plant is given an environment that matches its biological preferences, it can develop without the grower having to compensate. Mineral fertiliser can be reduced, liming is not needed, and fungal attacks that often appear in moisture-bound clay soils are rarer.\n\nFor hemp, this also means that the short Nordic growing season can be used without the soil simultaneously working against it. The season is not a limitation on Gotland; it is part of the place's character.\n\n## What Gotland soil is not\n\nNot all Swedish hemp is processed from raw material grown under the same conditions. On the mainland, especially in central Sweden, common agricultural land is primarily clay or moraine soil. Both have their strengths — clay binds nutrients, moraine releases water — but neither offers the same combination as Gotland.\n\nThe soil we are talking about also has a practical consequence: it is less prone to moisture-bound fungus. When moisture does not linger in the soil, the conditions for several fungal attacks that otherwise force growers into early interventions are reduced. On Gotland these interventions are needed less often — not because the grower is more skilled, but because the soil does not ask for them.\n\n## A historical note\n\nWhat is happening on Gotland today has precedent. During the Hanseatic era, Gotland was a hub of Baltic trade, and hemp was one of the goods the island was known for. Hemp's use in trade at that time was primarily industrial — rope, sails, canvas — and the quality of the Gotland material is described in contemporary sources as among Europe's finest. (For a more comprehensive history, see our e-book *The Nordic History of Hemp*.)\n\nWhen industrial hemp cultivation disappeared in Sweden during the 1960s, the bedrock and the climate did not disappear. The conditions remained; they were simply no longer used. They are what hemp growers on Gotland today have picked up again.\n\n## My relationship to the place\n\nWe are not growers. We are processors. What Helsama does is receive raw material from Gotland growers and prepare it for the consumer — not stand out in the field.\n\n\\n\n\nThe full journey from raw material to finished product — sorting, packaging, quality control — is described separately in the article [From Hemp to Finished Product](/en/kunskap/fran-hampa-till-fardig-produkt).\n\nBut what I have come to understand from my time on Gotland — as a five-year-old with a crystal in my hand, as an adult with a hemp harvest from Hempland — is that the geographical difference there is real. The local food tastes better. The local water is different. And the hemp is no different. It is the same limestone that gives a Gotland vegetable its character that gives a Gotland hemp harvest its.\n\nWhen you buy hemp from Helsama you get a product that is not geographically interchangeable. It would not have looked this way had it grown on the mainland, or on land selected primarily for price. You will notice this especially in our [Premium CBD Hemp](/en/produkt/premium-hemp-powder) — it is the first expression of limestone in the Helsama range. This is not a brand argument — it is a consequence of the limestone having been there first.\n\nThat is why we build Helsama where we build it.\n\n## Sources\n\n - Calner, M., Jeppsson, L. & Munnecke, A. (2004). \"The Silurian of Gotland — Part I: Review of the stratigraphic framework, event stratigraphy, and stable carbon and oxygen isotope development.\" *Erlanger geologische Abhandlungen*, Sonderband 5, 113–131. [researchgate.net/publication/237526335](https://www.researchgate.net/publication/285850124)\n\n - [Geological Survey of Sweden (SGU)](https://www.sgu.se/om-geologi/berg/sveriges-berggrund/) — Bedrock of Sweden\n\n - [International Commission on Stratigraphy](https://www.sgu.se/om-sgu/nyheter/2023/november/sgu-avlyssnar-den-gotlandska-berggrunden) — International Chronostratigraphic Chart\n\n - [Plants of the World Online](https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:306087-2) — Cannabis sativa L. (Royal Botanic Gardens, Kew)\n\n - [UNESCO World Heritage](https://whc.unesco.org/en/list/731/) — Hanseatic Town of Visby\n\n**Continue reading:** Related questions: [The Nordic climate advantage: 33% more CBDA on Gotland](/en/kunskap/nordens-klimatfordel-cbda), [What is Premium CBD – and Why Does Quality Make All the Difference?](/en/kunskap/premium-cbd-sverige) and [Hemp seed nutrition — vitamins, minerals and fatty acids in hemp seeds](/en/kunskap/hampans-naringsprofil).\n\n**About Helsama’s Premium CBD Hampa:** Unheated raw hemp is the only way to buy legal full-spectrum CBD — extracted full-spectrum oils are classed as narcotics and isolate isn’t full-spectrum. Helsama’s Premium CBD Hampa is exactly that: unheated, milled raw hemp grown on Gotland, and we’re the only ones selling the CBD hemp varieties grown in Scandinavia. The Nordic summer’s long light — up to 18 hours of daylight — makes the hemp special: our third-party analyses show 8.83% CBDA versus 6.64% for the same seed grown in Italy. [Read more about our hemp](/en/premium-cbd)."
}