Den tidligere grusgrav er privatejet og vi har fået ejerens tilladelse til at færdes der.
Området er moræneflade med bakker bestående af aflejringer fra isdæmmede søer, der efterfølgende blev overskredet under Bælthavsgenfremstødet, hvorved hver enkelt bakke blev tværet ud i isens bevægelsesretning og der dannedes terrænstribningen. I Gedebjerg Bakken findes et stort, meget instruktivt profil.
Området har stor forsknings- og undervisningsmæssig værdi, bl.a. fordi søsedimenterne giver værdifulde oplysninger om aflejringsforholdene på en dødismasse præget af arealnedsmeltning og en bedre forståelse af de store dele af det danske bundmorrænelandskab, som er dannet af aktivt strømmende ismasser.
Landskabet vest for Kundby er præget af en del af disse mindre bakker, som er 20-25 meter høje og 100-200 meter i tværmål. Én af disse hatformede bakker er Gedebjerg bakken, hvor der tidligere har været grusgrav og derfor er det blevet muligt at se lagene i bakken. Vi ved, at lagene af grus, sand, finsand og ler må være aflejret i vand. I grusgraven ses imidlertid disse lag mere opretstående og denne proces er sket i slutningen af sidste istid for 15.000 år siden. Gletsjeren smeltede langsomt, da klimaet var blevet mildere. Isen smeltede ikke jævnt, men efterlod sig større og mindre områder, hvor der stadig lå is, som ikke mere havde forbindelse med gletsjeren. Disse isrester kaldes for dødis. Dødismasserne kan have været flere hundrede meter tykke. De smeltede langsomt som tiden gik, og isens indhold af ler, sand, grus og sten blev skyllet bort af smeltevandet gennem smeltevandsfloder, der opstod på isens overflade. Der opstod ofte også søer på isens overflade. Smeltevandet tømte sin ladning af sedimenter ud i disse søer. Da isen var smeltet helt bort lå tilbage flade bakker som kaldes Kamebakker.
Senere blev det kortvarigt koldere. Vandet i jorden og i bakkerne frøs, så de løse lag af sand, grus og ler blev hårde som sten. Gletsjeren rykkede atter frem og bakkerne som lå i vejen blev bulldozet af isen således, at især de centrale dele af bakkerne blev deformerede sådan, at de før vandrette segmentlag blev skubbet og væltet op, så de kom til at stå mere eller mindre stejlt. Toppen blev kuppelformet og bakketypen kaldes dislokerede kámes eller hatformede bakker.
De to øverste tegninger viser dannelsen af kamebakker og de tre nederste viser dannelsen af hatformede bakker, hvor de frosne lag bliver skubbet op.
Hatformede bakker er almindelige på Langeland, hvor de ligger fordelt på 3-4 rækker, der følger øens længderetning og afspejler et israndsstrøg parallelt med øen. Bakkerækken fortsætter på bunden af Storebælt for så igen at kunne ses ved Korsør.
Kilder: Nationalkomiteen for geologi. Naturen i Danmark, Geologien, 2. udgave. Naturstyrelsen, Geologi.
Spørgsmål:
NB Det er forbudt at kravle op eller gå tæt på skrænten p.gr.a. af faren for nedskred!
Stage 1:
a) Se på profilen og beskriv farven og lagene?
b) Angiv hældningen (0-90 grader) af lagene på den nedre og øvre del af skrænten?
c) Hvilken retning har skrænten?
d) Hvilken retning har isen bevæget sig for at omdanne bakken? Hvordan kan du se det?
Stage 2:
e) Beskriv lagene her, form og hældning?
f) Mellem dig og skrænten er der nogle små bakker. Hvor mange og hvad består de af?
Send svarene til vores profil, du må gerne logge straks.
The former gravel pit is privately owned and we have got the owner's permission to go there.
The area is a morainesurface with hills consisting of deposits from lakes surrounded with ice, which were subsequently exceeded during The Bæltsea ice offensive whereby each layer was pushed in the ice movement direction and formed terrain stripes . In Gedebjerg Hill is a large, very instructive profile.
The area has great research and educational value, because the lake sediments provide valuable information on the deposition conditions on a dead ice mass characterized by melting and a better understanding of the major parts of the Danish ground moraine formed by actively flowing ice.
The landscape west of Kundby is characterized by a number of these small hills which are 20-25 meters high and 100-200 meters across. One of these hat-shaped hills are Gedebjerg hill where previously open pit and therefore, it has been possible to see the layers in the tray. We know that the layers of gravel, sand, fine sand and clay may be deposited in the water. In the gravel pit seen, however, these layers more going up and this process has happened in the last Ice Age 15,000 years ago. The glacier melted slowly, when the climate was milder. The ice did not melt completely, but left larger and smaller areas where there was still ice that no more was linked to the glacier. These ice left is called dead ice. The dead ice may have been hundreds of meters thick. The ice melted slowly as time passed and the ice content of clay, sand, gravel and stones were washed away by the melt water through glacial streams that occurred on the ice surface. There was also often lakes on the ice surface. The melt water emptied his load of sediments in these lakes. When the ice had melted completely away lay back flat hills called camehills.
Thereafter, it was briefly colder. The water in the soil and in the hills froze, so the loose layer of sand, gravel and clay was hard as stone. The glacier moved forward again and the hills lying on its way was bulldozed by the ice so that especially the central parts of the hills were deformed such that the horizontal layers was pushed up, so they came to stand more or less steeply. The top of these hills were dome-shaped and this type of hill is called dislocated Kámes or hat-shaped hills.
The upper two drawings show the formation of the came hills and the three in bottom show the formation of the hat-shaped hills, where the frozen layer is pushed up into flakes.
Hat-shaped hills are common on Langeland, where they are spread over 3-4 rows that follow the island's longitudinal direction and reflects a glacial parallel to the island. Tray series continues at the bottom of the Great Belt and can again be seen by Korsor.
Sources: National Committee for Geology. Nature in Denmark, geology, 2nd edition. Nature Agency, Geology.
Question:
NB It is forbidden to climb up or go near the cliff because of the danger of down fall
Stage 1:
a) Look at the profile and describe the color and layers?
b) The gradient (0-90 degrees) of the layers on the lower and upper part of the slope?
c) Which direction is the slope?
d) Which direction has the ice moved to transform the hill? How can you see it?
Stage 2:
e) Describe the layers here, shape and gradient?
f) Between you and the slope, there are some small hills. How many and what do they consist of?
Send answers to our profile, you are allowed to log immediately.