Sandstenfacaderne i Amalienborg

The Sandstone Façades in Amalienborg

🇬🇧 Please keep your distance from the guards. Be respectful. 🇩🇰 Hold afstand til vagterne. Vær respektfuld.

🇩🇰 DANSK 🇩🇰 (English below!)

Amalienborg har fire paladser bygget i midten af ​​det 18. århundrede til adelige familier. Efter en brand i 1794 ødelagde det tidligere kongelige palads, flyttede den danske kongefamilie ind og har boet der lige siden. Paladserne blev bygget af importeret Obernkirchener-sandsten fra Nordtyskland, en finkornet sandsten kendt for sin holdbarhed og ensartede tekstur. Stenen kan ses i facaderne på alle fire paladser: nogle fra det 18. århundrede, og nogle blev udskiftet under renoveringer i slutningen af ​​det 20. århundrede.

Sandstensformation

Sandsten dannes, når små mineralkorn aflejres og forlitres over tid. Først nedbrydes eksisterende bjergarter til mindre partikler ved fysisk og kemisk forvitring. Disse partikler transporteres derefter til nye steder, oftest via vand i floder eller have. Afhængigt af transportmetodens energi kan sedimenterne sorteres eller afrundes forskelligt. Over tid lægger disse sedimenter sig på ét sted i lag. Vægten af ​​de øvre lag komprimerer de nedre lag, mens mineraler fra grundvandet fylder mellemrummene i sedimentet og cementerer sammen til sandsten.

Obernkirchener-sandstenen begyndte specifikt at blive dannet for omkring 140 millioner år siden, i Berrias-tiden i kridttiden, da det nordlige Tyskland var tropisk. Bückeberg-højden lå ved kystlinjen af ​​et hav, der tilhørte det gamle Tethys-hav. Kraftige floder flød fra de sydlige lande og aflejrede sedimenter i havet.

Kornstørrelse

Finkornet sandsten dannes normalt i roligere miljøer, såsom søer eller langsomt strømmende floder, hvor kun små sedimenter bundfælder sig. Mellem- og grovkornet sandsten er mere tilbøjelig til at dannes i miljøer med høj energi, såsom floder eller strande, hvor større korn kan aflejres. Kornstørrelsen er defineret som den gennemsnitlige diameter af sandpartiklerne i klippen.

Finkornet: 0.0625–0.25 mm
Mellemkornet: 0.25–0.5 mm
Grovkornet: 0.5–2 mm

Sortering og Tekstur

Jo længere sedimentet blev transporteret, før det satte sig, desto mere velsorteret kan stenen fremstå. Hvis kornstørrelserne synes at være meget ensartede - ikke meget variation - er sedimenterne velsorterede. Med mere variation i størrelse er det sandsynligt, at sedimenterne er blevet transporteret over en kortere afstand, før de satte sig, hvilket ikke tillader større korn at adskille sig fra mindre korn.

Derudover vil sediment, der er blevet transporteret længere, have korn med glattere kanter. Dette skyldes, at kornene blev poleret af vandet eller vinden, de blev transporteret af, hvilket udglattede deres oprindeligt ru kanter. Det er muligt, at kornene er blevet glattet nok til, at den endelige sandsten fremstår næsten poleret.

Farve

Sandstenens farve afhænger hovedsageligt af dens mineralsammensætning. Det meste sandsten har 50-90% kvarts, hvilket giver klippen dens karakteristiske lysegule eller cremefarve. Andre mineraler kan tilføje subtile nuancer:

• Røde/orange/brune toner: Jernoxider, glimmer eller feldspat
• Grå/blågrå toner: Fine lerindeslutninger

Derudover ændrer forvitring sandstenens udseende over tid.

• Kemisk forvitring: Spor af jern i sandstenen kan reagere med ilt og fugt, hvilket skaber røde eller brune striber, der mørker stenen. Sur regn eller anden forurening kan også mattere eller gøre overfladen mørkere.
• Fysisk forvitring: Ved lang eksponering for vind, regn og frostcyklusser kan stenens kanter blødgøres, og overfladestrukturen kan ændre sig.
• Biologisk forvitring: Mos, laver og andre små planter kan forårsage mørkegrønne pletter i fugtige områder.

Amalienborg har haft adskillige restaureringsprojekter i sin historie, som har fjernet eller repareret mange tidligere tegn på forvitring. Dog er ikke alt blevet fuldstændig renoveret, og forvitringen er altid i gang, så der kan stadig findes tegn på forvitring.

Spørgsmål

Du kan besvare alle spørgsmål uden online research, blot ved at læse beskrivelsen og være på stedet. Send venligst spørgsmålene til mig via Beskedcenteret eller via e-mail.

1. Er sandstenens kornform fin-, mellem- eller grovkornet? Hvad forårsagede Obernkirchener-sandstenens udseende? OBS: KOM IKKE for tæt på hovedfacaderne, det vil vagterne ikke kunne lide! Du kan komme tættere på i en af ​​de fire indgange, eller du kan få en god idé om svaret på afstand.

2. Besøg hvert af de fire paladser (se waypoints på denne cache). Vælg et sted på et af paladserne, der ser ud til at være blevet påvirket af forvitring. Hvilken type forvitring har det udholdt? Også fortæl mig, hvilket palads du valgte, og hvilke beviser fører dig til denne konklusion.

3. Er der et palads, der ser ud til at være mindre forvitret end de andre? Hvilket er det, og hvorfor tror du det?

4. (Valgfrit) Tag et billede med dig selv, dit geonavn, eller en unik genstand for dig med dit yndlingspalads i baggrunden. Fortæl mig i din log, hvorfor det er dit yndlingspalads!

🇬🇧 ENGLISH 🇺🇸

Amalienborg features four palaces constructed in the mid 18th century for noble families. After a fire in 1794 destroyed the previous royal palace, the Danish royal family moved in, and has lived there ever since. The palaces were built using imported Obernkirchener sandstone from northern Germany, a fine-grained sandstone known for its durability and uniform texture. The stone can be seen in the façades of all four palaces: some from the 18th century, and some replaced during renovations in the late 20th century.

Sandstone Formation

Sandstone is formed when small mineral grains are deposited and lithified over time. First, existing rocks are broken down into smaller particles by physical and chemical weathering. These particles are then transported to new locations, most often via water in rivers or oceans. Depending on the energy of the method of transportation, the sediments may be sorted or rounded differently. Over time, these sediments settle in one location in layers. The weight of the upper layers compress the lower layers, while minerals from groundwater fill the spaces in the sediment, cementing together to form sandstone.

Obernkirchener sandstone specifically started forming about 140 million years ago, during the Berrias age of the Cretaceous period, when northern Germanyused to be tropical. The Bückeberg elevation was located on the coastline of a sea that belonged to the ancient Tethys ocean. Powerful rivers flowed from the southern lands and deposited sediments into the ocean.

Grain Size

Fine-grained sandstone normally forms in calmer environments, such as lakes or slow-moving rivers where only tiny sediments settle. Medium- and coarse-grained sandstone is more likely to form in high-energy environments like rivers or beaches, where larger grains are able to be deposited. The grain size is defined as the average diameter of the sand particles seen in the rock.

Fine-grained: 0.0625–0.25 mm
Medium-grained: 0.25–0.5 mm
Coarse-grained: 0.5–2 mm

Sorting and Texture

The further sediment was transported before it settled, the more well-sorted the stone may appear. If grain sizes seem to be very consistent - not a lot of variance - the sediments are well-sorted. With more variation in size, the sediments are likely to have been transported a shorter distance before settling, not allowing larger grains to separate from smaller grains.

Additionally, sediment that has been transported further will have grains with smoother edges. This is because the grains were polished by the water or wind they were transported by, smoothing their originally rough edges. It is possible for the grains to be smoothed enough that the final sandstone appears almost polished.

Color

The color of sandstone depends mainly on its mineral composition. Most sandstone has 50-90% quartz, giving the rock its signature pale yellow or cream color. Other minerals can add subtle hues:

• Red/orange/brown tones: Iron oxides, mica, or feldspar
• Gray/blue-gray tones: Fine clay inclusions

Additionally, weathering changes the appearance of sandstone over time.

• Chemical weathering: Traces of iron in the sanstone can react with oxygen and moisture, which creates red or brown streaks that darken the stone. Acid rain or other pollution can also dull or darken the surface.
• Physical weathering: With long exposure to wind, rain, and freeze cycles; edges of the stone can soften and surface texture can change.
• Biological weathering: Mosses, lichens, and other small plants can cause dark green patches in damp areas.

Amalienborg had several restoration projects in its history, which has removed or fixed many past evidence of weathering. However, not everything has been completely redone, and weathering is always ongoing, so signs of weathering can still be found.

Questions

You should be able to answer all questions without online research, just by reading the description and being at the location. Please send the questions to me via Message Center or via email.

1. Is the grain of the sandstone fine-, medium-, or coarse-grained? What caused Obernkirchener sandstone to be like this? NOTE: DO NOT get too close to the main façades, the guards will not like it! You can get closer in one of the four entrances, or you can get a good idea of the answer from a distance.

2. Visit each of the four palaces (see the waypoints on this cache). Pick a spot on one of the palaces that appears to have been affected by weathering. Which type of weathering did it endure? Also tell me which palace you picked, what evidence lead you to this conclusion.

3. Is there a palace that appears to be weathered less than the others? Which one is it, and why do you think this?

4. (Optional) Take a photo with yourself, your Geocaching name, or a unique item to you with your favorite palace in the background. Tell me in your log why it's your favorite!

Sources

https://www.britannica.com/science/sedimentary-rock/Sandstones
https://obernkirchener-sandstein.dk/en/genesis-geology
https://de.wikipedia.org/wiki/Obernkirchener_Sandstein
https://en.wikipedia.org/wiki/Sandstone
https://europeanheritageawards-archive.eu/laureates-1978-2022/detail/restoration-of-christian-viis-mansion-copenhagen
https://aabergarchitects.com/portfolio-items/amalienborg-the-royal-residence/