구조토 형성 모델

Organized topographic features: (a and b) stone polygons, Svalbard

An Introduction to Physical Geography and the Environment by Joseph Holden (pearson) - 515 page

 

 

 

위와 같은 구조토가 어떻게 만들어지느냐? 물어보면

 

 

'이렇게 만들어진다'
라고 대답해왔는데

 

다시 생각해보니
저 모델가지고, 맨위의 사진을 도대체 설명할 수가 없습니다.

 

왜냐하면

저 모델에서는 자갈의 고도는 무조건 가운데 봉우리 보다 낮아야 하는데
사진을 보면 봉우리보다 자갈이 더 높기 때문입니다.

 

 

Inferred soil circulation patterns resulting in sorted circles. (Source: after Hallet et al. , 1988)

An Introduction to Physical Geography and the Environment by Joseph Holden (pearson) - 515 page

 

이 모델로 설명하면 가능할 듯 합니다.

 

"활동층에서 gravel과 fine materials가 구분되고
대류 운동을 통해 돌을 떠 밀어올리는 것"이 아닐까??"

하는 생각을 해봤습니다.

 

* 지형학(권혁재)책에서는 지하 1m두께 이내에서는
동결 융해를 반복하면 분급현상이 나타난다고 하네요.

 

 

위의 책에서는 이런 가설을 내세우고 있습니다.
(대류현상이 일어나는 매커니즘 설명)

One hypothesis involves convection within the ground. In summer,
saturated soil close to the ground surface warms during the day whereas water at depth remains colder.

 

Since water is densest at 4°C the colder water at depth is less dense than the water close to the surface,
and this drives convection. Descending warm water can then melt the frozen surface below
resulting in an undulating interface between frozen and unfrozen ground that is reflected in the surface topography. 

 

Sorting of the soil particles can occur if the soil particles convect with the soil water ( Figure 17.23 ). 

 

 

또 다른 패턴의 구조토가 있습니다.

stone stripes

An Introduction to Physical Geography and the Environment by Joseph Holden (pearson) - 515page

 

(a), (b)와 (c)의 가장 큰 차이는 바로 경사도 입니다.

경사도가 30도 이상 넘으면 돌맹이가 흘러서 원형이나 다각형을 만들 수가 없고
저렇게 길쭉한 모양으로 늘어서게 됩니다.

 

 

 

Exceptionally well-developed patterned ground. (a) Circular domains of fine-grained soil approximately 2 m in diameter ringed by gravel approximately 0.25 m high, Broggerhalvoya, NW Spitsbergen. (b) Looking up an approximately 12° slope at narrow sorted stripes approximately 0.15 m wide, near summit of Mauna Kea, HI, USA. (c) Looking down an approximately 3–4° slope at non-sorted stripes approximately 4 m wide with distinct 10–20 cm microrelief and deep vegetated troughs, Thule, northwest Greenland. (Online version in colour.)

http://rsta.royalsocietypublishing.org/content/371/2004/20120357

 

 

(a) Highly idealized long-term soil motion inferred from measured surface soil displacements. (b) More realistic pattern of soil motion consistent with surface data [29]. Image provided courtesy of Albert Pissart.

http://rsta.royalsocietypublishing.org/content/371/2004/20120357

 

 

(a) Vertical section across a sorted circle showing the microrelief and textural domains. (b) Sensor locations: H, heave transducers; T, tilt and temperature cells with anticipated long-term rotation direction shown and Por, pore pressure transducers.

http://rsta.royalsocietypublishing.org/content/371/2004/20120357

 

 

 

 

 

 

 

Key Concepts in Geomorphology by Paul R. Bierman, David R. Montgomery (2013) - 321page

 

 

 

 

 

 

 

 

Earth Environments - Past, Present and Future by David Huddart, Tim Stott (2010) Wiley - 572page

 

 

 

(a) Frost sorting of soils according to the frost pull (top) and frost push (bottom) mechanisms. 
(b) Movement of coarse and fine soil due to freezing and thawing. 
(Source: after Ballantyne and Harris, 1994)

 

 

 

https://www.sciencenews.org/article/ice-needles-freeze-thaw-patterns

Here’s how ice needles sculpt patterns into cold, rocky landscapes