Ask the Field Tutor
Below are nine questions that walkers, photographers, and geology students most frequently ask when standing before a Norwegian roadcut, fjord viewpoint, or high-mountain pass. Click any question to expand the full field notes.
Landscapes, Fjords & Glacial Processes
01. Why are Norwegian mountains often flat plateaus on top instead of sharp peaks?
When you climb out of a steep fjord valley onto Hardangervidda or Finnmarksvidda, the terrain suddenly flattens into an undulating tableland. That plateau is an ancient erosional plain (often tracing back to the Sub-Cambrian or Mesozoic peneplains) that was worn flat near sea level, then uplifted vertically as a broad dome during the Cenozoic Era (~60–20 million years ago). Quaternary glaciers subsequently sawed deep U-shaped troughs into the margins of the uplifted dome, while thinner, cold-based ice over the flat interior preserved the high plateau surface. Sharp alpine peaks (like Hurrungane or the Lyngen Alps) occur only where closely spaced cirque glaciers ate backward until their headwalls met.
02. Why are glacial lakes like Oldevatnet and Gjende such a vivid turquoise-green colour?
Look closely at a bottle of water dipped from the inflow stream of Lake Gjende or Lovatnet: it appears milky grey. Glaciers grind bedrock into microscopic mineral silt (0.002 to 0.06 mm across) called rock flour (bre-slam). When this silt pours into a deep, quiet lake, the coarse sand settles at the delta while the finest clay and silt stay suspended in the water column, reflecting and scattering green and turquoise wavelengths of sunlight.
03. How can older rocks sit on top of younger rocks in Jotunheimen and Hardangervidda?
In undisturbed sedimentary basins, the oldest layer is always at the bottom. However, during the Caledonian Orogeny (490–390 million years ago), the collision between Laurentia and Baltica sheared off huge horizontal slabs of ancient Proterozoic crust—called thrust nappes (skyvedekker)—and shoved them up to 200+ kilometres southeastward over younger Cambrian and Ordovician marine shales.
04. Are Norway’s glaciers uninterrupted leftovers from the last Ice Age?
No. Sediment cores drilled from lakes downstream of Jostedalsbreen and Hardangerjøkulen show a period between roughly 8,000 and 5,000 years ago (the Holocene Thermal Maximum) when summer temperatures were 1.5°C to 2°C warmer than mid-20th-century norms and rock flour disappeared from the lakes. Almost all Norwegian glaciers melted away completely, then reformed during the Neoglacial cooling around 4,000 years ago, reaching their greatest post-ice-age size during the Little Ice Age around 1750 CE.
05. Why is Sognefjorden deeper inland than where it meets the ocean?
Rivers cannot excavate below sea level, but a 2,000-metre-thick glacier remains grounded on the bed even in deep water. Where confluent ice streams funnelled through the narrow mid-fjord bedrock trough, basal ice velocity and downward pressure reached a maximum, gouging Sognefjorden down to 1,308 metres below sea level. Near the outer coast, the ice spread out and began to float, leaving a shallow bedrock threshold (fjordterskel) only 100–200 metres deep.
Field Identification, Regulations & Maps
06. Is it legal to hammer rocks or collect mineral samples in Norway?
Always separate observation from extraction. Under Norway’s Outdoor Recreation Act (Friluftsloven), walkers may pick up small, loose surface stones on uncultivated land outside protected zones for personal educational interest. However, using a geological hammer, chisel, or drill on solid bedrock outcrops—especially glacially polished svaberg or roadcuts—damages irreplaceable features and requires landowner permission. Inside National Parks, Geoparks, and Nature Reserves, removing rocks or minerals is strictly prohibited. Our field rule: photograph with a scale, use a hand lens, and leave the outcrop intact.
07. What causes the giant cylindrical holes (jettegryter) in valley bedrock?
Folklore attributed these smooth cylindrical wells to giants churning porridge, hence the name jettegryter (giants’ cauldrons). Geologically, they form where fast, turbulent meltwater—either in a modern gorge or beneath a melting ice sheet under high hydrostatic pressure—creates a stationary whirlpool. Hard granite cobbles trapped in the depression spin continuously, grinding a vertical shaft metres deep into solid gneiss.
08. How do I tell whether a valley boulder was dropped by a glacier or fell from the cliff above?
Check two clues: angularity and lithology. A rockfall boulder (ur-blokk) at the base of a cliff has razor-sharp, unweathered fracture edges and matches the exact mineral composition of the cliff directly overhead. A glacial erratic (flyttblokk) typically shows bruised, sub-rounded corners, flattened facets with parallel scratches, may sit perched on an open plateau far from any cliff, and often consists of a rock type carried from twenty or fifty kilometres up-valley.
09. Where can walkers consult official geological bedrock maps before a trip?
The Geological Survey of Norway (NGU — Norges geologiske undersøkelse) publishes open-access digital map viewers covering both Bedrock (Berggrunn N250/N50) and Quaternary superficial deposits (Løsmasser). Before driving a mountain pass, check the bedrock map to spot where roadcuts cross thrust boundaries between Precambrian basement and Caledonian nappes.