Siljansringen

Part 1 - Knowledge acquisition

365 million years ago, a meteorite struck and formed what is now known as the Siljansringen. In the Siljansringen, Lake Siljan is the clearest trace of the meteorite. The maximum depth of Lake Siljan is 134 meters. The Siljansringen is the largest known meteorite impact site in Europe.

Read and listen:

• Sveriges Radio (7:39): Evidence of the meteorite impact in Siljansringen (in Swedish, new window)
• Article from Forskning.se about: Ancient life discovered in Siljan's meteorite crater (in Swedish, new window )
• Geological Survey of Sweden, SGU (in Swedish, new window)
• Siljan Geopark (in Swedish, new window)

Part 2 - Investigate and describe

In Geoskolan's map tool, you can find elevation contours, soil type map, watercourses and lakes, and vegetation. Find out and describe by studying the map layers in the map tool:

Locate Siljansringen

• Which map layer do you think best shows Siljansringen? Discuss and justify.
• Which larger lakes are part of Siljansringen?

Here's how to do it:

1. Open Geoskolan's map tool and search for Siljan.
2. Click on the Map Layers icon in the top left corner.
3. Click on the plus sign (+) next to “Flygfoton och höjddata”, the Aerial Photos and Elevation Data category.
4. Then choose a map layer by clicking on either “Ortofoto – färg”, or “Ortofoto – infrarött”, or “Höjdmodell – terrängskuggning” (Orthophoto - Color, Orthophoto - Infrared, or Digital Elevation Model - Terrain Shading).
5. Summarize your answers to the tasks and present them along with map images.

Measure and compare

• What is the diameter of Siljansringen/crater?
• How much of Stockholm would the impact of Siljansringen's meteorite cover?

Here's how to do it:

1. Open Geoskolan's map tool (new window) and search for Siljan.
2. Click on the Draw tool in the menu on the right side of the map window.
3. Select Create Line.
4. Measure by placing a point at the center of Siljansringen and another point at the outer edge of the ring.
5. Read the distance.
6. Pan the map and zoom in on Stockholm.
7. Determine how much of the Stockholm area would be covered by the meteorite impact by measuring the same distance, starting from the center of Stockholm.
8. Summarize your answers to the tasks and present them along with map images.

Population around Siljansringen

• Which towns in Siljansringen are the most densely populated?
• What color is used to show the most densely populated areas?

Here's how to do it:

1. Open Geoskolan's map tool and search for Siljan. Use the Zoom and Pan tools to study the area around Siljan with the towns of Leksand, Mora, Orsa, Skattungbyn, Furudal, Boda, and Rättvik.
2. Click on “Kartlager” (Map Layers) icon in the top left corner.
3. Click on the plus sign (+) next to the category “Samhälle” (Society).
4. Then click on the checkbox next to the map layer “Totalbefolkning” (Total Population).
5. Summarize your answers to the tasks and present them along with map images.

Protected areas

There are two protected areas according to Natura 2000 on Sollerön in Siljan.

• Explain why these areas are protected.
• There are several protected areas in Siljansringen. Find out where.

Here's how to do it:

1. Open Geoskolan's map tool and search for Siljan, zoom in on Sollerön.
2. Click on the icon “Kartlager” (Map Layers) in the top left corner.
3. Click on the plus sign (+) next to the category “Biologi” (Biology).
4. Then click on the checkbox next to the map layer “Skyddade områden (Natura 2000)”, Protected Areas (Natura 2000).
5. Summarize your answers to the tasks and present them along with map images.

Tip:

Measure distance between two points, right-click and select show height. A graph is then displayed with an elevation profile for your measured distance. For the mouse pointer over the graph, a high point is marked in the map.

Part 3 - Analyse, explain and present

Vasaloppet

Vasaloppet takes place between Sälen and Mora, located near Siljansringen.

Which part of the race do you think is the most challenging?

Here's how to do it:

1. Open Geoskolan's map tool. Search for Mora and Sälen. Pan and zoom to see both towns on the map.
2. Click on the Draw tool “Rita” in the menu on the right side of the map window.
3. Select Create Line, “Skapa linje”. Draw a line between Sälen and Mora.
4. Compare the elevation contours along the route on the map.
5. Click on the Map Layers icon “Kartlager” in the top left corner.
6. Click on the plus sign (+) next to the Aerial Photos and Elevation Data category, “Flygfoton och höjddata”.
7. Then click on the checkbox next to “Höjdmodell – terrängskuggning “, the Digital Elevation Model - Terrain Shading map layer.
8. Use the Change Transparency function to easily identify features with the help of the base map.
9. Summarize your answers to the task and present them along with map images.

Water level in Siljan

Water levels in Siljan can vary significantly, up to one meter. Analyze and explain the factors that may contribute to this using different map layers in Geoskolan's map tool.

• What geological factors affect the water level? For example, mountains and water inflows.
• Summarize your answers to the task and present them along with map images.

Additional Lesson Suggestions

SGU's digital educational initiative Geologisk (in Swedish, new window) which explores the interaction between geology, natural resources, sustainability, and urban planning.