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地球生物絶滅の痕跡 ~ Deep Impact ~

A cache by hikohohodemi Send Message to Owner Message this owner
Hidden : 05/06/2019
2 out of 5
2.5 out of 5

Size: Size:   other (other)

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Geocache Description:

注意事項 (Please note)
GZは海岸にあります。満潮時には近寄れない時がありますので、事前に潮位を確認ください。  (潮見表 )
GZ is on the coast. There are times when you can not get close at high tide, so check the tide level in advance.


This picture is the "Manicouagan Crater" (Quebec, Canada) seen from the International Space Station. This size is a huge 100km in diameter, and it was formed by the collision of huge meteorites about 215 million years ago.And at this time, the marine creatures on the earth were extinct due to the impact of the collision.
Traces of this extinction were found in the stratum near Ajirojima Island.And, at Ajirojima Island, we can see the traces of the mass extinction of organisms that occurred about 250 million years ago. The area around Ajirojima Island is a globally valuable place where traces of extinction are left.


In the history of the earth, we know that biological extinction has occurred 5 times.
Please check the figure below. This represents the "Big 5 of extinction" in the Phanerozoic since the Paleozoic Cambrian (540 million years ago). Note: The Phanerozoic means "the age when living creatures that can be seen with the naked eye inhabit".
The Big 5 refers to,①the extinction of trilobite etc., ②primordial fish extinction, ③largest extinct organisms mass extinction in history, ④marine creatures extinct, and ⑤dinosaur extinction.
Although ④ and ⑤ are caused by meteor impact, but, ①~③ do not have a clear cause.

出典:「生物の科学遺伝 Vol.66 No.5」株式会社エヌ・ティー・エス
Source: "Science and genetics of organisms Vol.66 No.5" NTS Inc.


Let's examine what trace was found Ajirojima Island and around there.


《③The largest biological mass extinctions in history》
On Ajirojima island, we can refer to "black shale" and "red, purple and green cherts".
The black shale is a stratum formed immediately after the mass extinction of organisms. At that time there was very little air (oxygen) in the sea. Organic matter such as sludge, and iron sulfide were deposited to form a shale.
The chert is the result of the deposition of marine zooplankton called radiolaria.The "Triassic", where the chert was made, is the time immediately after the largest mass extinction of organisms in the history of the Earth.When oxygen recovers to the sea, iron in the chert and oxygen react to form iron rust (iron oxide) and become red.The color change on this chert is said to record how oxygen recovered to the ancient sea.

三畳紀後期のチャートから、大きさ 1mm 以下の放散虫等の化石を調べたところ、隕石衝突直後に非常に高い割合でこれら化石群集が絶滅していることが分かりました。(研究は岐阜市で採取された試料で行われました)

《④Marine creatures extinction》
Traces of the meteor impact that made the Manicouagan Crater were found in 2016 at a distance of only 1 km from Ajirojima Island. (Please refer to the figure below)
Researchers examined fossils such as radiolarians with a size of 1 mm or less in the Late Triassic chert. Then, it turned out that these fossil assemblages are extinct at a very high rate immediately after the meteor impact. (Study was conducted on samples collected in Gifu City)

出典:「新聞発表資料」(2016.07.08) 熊本大学
Source: 「Press Release」(2016.07.08) Kumamoto University

1. 以下のTASKを実行してください。
3. 答えはログに記入しないでください。

1. Please carry out following TASK.
2. Please send e-mail this cache name and the answer to following questions to cache owner.(hikohohodemi)
3. Do not include this answer in your on-line log.
4. You do not need to wait for confirmation from me before posting online.

Please Arrange the four rocks correctly in chronological order. A. Red Chert, B. Green Chert, C. Purple Chert, D. Black Shale
Ex) A,B,C,D

The black shale contains no plankton.
Why is that? Please state your thoughts.

Please collect 4 colored rocks fragments at the shore, take a picture of these and upload it to the log.

Additional Hints (No hints available.)

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