거북바위의 형성과정 거북바위는 파도의 침식으로 형성된 거북모양의 시스택이다. 거북바위의 동쪽은 평탄하고 서쪽은 울퉁불퉁하다. 이것은 좌우의 암질이 다르기 때문인데, 동쪽은 단단한 포놀라이트 암맥이 버티고 있고, 서쪽은 침식에 약한 집괴암과 용암이 분포한다.
Turtle Rock, a kind of sea stack, was formed by differential erosion. There is a difference in erosion pattern between the east and west sides of Turtle Rock due to its different geology. Basaltic agglomerate is distributed on the west side, whereas phonolitic dike with hard and dense characters is distributed on the east side of the rock mass, respectively. As resistance to erosion depends on rock types such as dike, joint, lava and agglomerate, interesting morphological textures develop on Turtle Rock. Various forms of volcanic rocks are observed on Turtle Rock.
클링커(Clinker)
점성이 높은 아아 용암이 식으면서 껍질이 깨져 생성된 조각. The surface of aa lava with high viscosity is exceedingly rough, covered with a layer of partly loose, very irregular fragments commonly called clinker.
냉각대(Chilled margin)
냉각대 암맥의 가장자리가 빠르게 식어 유리처럼 매끈하면서 검은색을 띄는 부분. A shallow intrusive or volcanic rock texture characterized by a glassy or fine grained zone along the margin where the magma or lava has contacted air, water or particularly much cooler rock.
용암 흐름구조(Lava Flow)
경사면을 따라 용암이 반복적으로 흐른 흔적. Repetition of lava flow on the surface of tephra deposited on a volcano.
A(A)
점성이 높은 아아 용암이 경사면을 따라 흐르는 동안 클링커와 용암 덩어리가 눈덩이처럼 달라붙어 만들어진 공모양의 화산암덩어리. A rounded ball of lava that occurs on the surface of aa lava flow. Lava balls grow when a small fragment of solidified lava rolls along the surface of active flow and lava sticks or accretes to its surface. The growth of a lava ball is similar to the way a giant snowball grows when soft, sticky snow adheres to its surface as it rolls down slope. It grows larger than 3 meters in diameter.
- 시스택(Sea stack) : 다음 어스캐시를 참고하세요. Pease refer to the following Earthcache! Chotdaebawi rock(추암 촛대바위)
- 암맥(Dyke) : 마그마가 기존의 암석 속으로 뚫고 들어와 굳어진 것 A dike or dyke, is a sheet of rock that is formed in a fracture in a pre-existing rock body.
- 아아 용암(Aa lava) : 점성이 커서 표면이 거칠고 상부와 하부에 1～2m 두께의 클린커층을 형성하며 중앙부는 비교적 치밀한 용암 상태를 이루는 것이 특징이다. Aa forms when lava flows rapidly. Under these circumstances, there is rapid heat loss and a resulting increase in viscosity. When the solid surface crust is torn by differential flow, the underlying lava is unable to move sufficiently rapidly to heal the tear. Bits of the crust are then tumbled in and coated by still liquid lava, forming the chunks.
- 포놀라이트(Phonolite) : 다음 어스캐시를 참고하세요. Pease refer to the following Earthcache! Mushroom Rock
- 집괴암(Agglomerate) : 다음 어스캐시를 참고하세요. Pease refer to the following Earthcache! Bongrae Waterfall
[로그하는 방법]
- 거북바위 시스택의 전 단계인 시아치는 거북바위의 어느쪽에 있었을까요? 그렇게 판단한 근거는 무엇인가요?
- 거북바위에 형성된 "A"는 무엇인가요? "A"의 크기는 얼마나 되나요?
- 거북바위를 배경으로 당신 또는 당신의 GPS를 찍은 사진을 로그에 올려주세요. (선택사항이지만 사진을 올려주시기를 부탁드립니다.)
- 답을 제 Profile에 있는 메시지창을 이용해 제게 보내주세요. 이제 로그하셔도 됩니다. 답에 문제가 있을 경우 제가 메시지를 드리겠습니다.
[How to log]
- The previous stage of 'sea stack' is 'sea arch'. On which side of the Turtle Rock was 'sea arch' supposed to be located? Why do you think so?
- What is an "A" formed on Turtle Rock? How big is "A"?
- Upload the photo of you or your GPS with Turtle Rock at the cache zone in the background! (The task is optional but I would highly appreciate if you would do so.)
- Please send the answers to me by message on my profile! You may log as 'Found'. If the answer is not correct, I will contact you.
*** Terrain rating : If you are in Ulleungdo island, it would be 1.5 instead of 4.5.
Ref : Ulleung County, Wikipedia
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