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Geological timescale (地質年代)

Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily

Agassiz, Jean Louis Rodolphe (1807-1873)

Swiss-born American biologist and geologist
1837 proposed the presence of ice age (glacial age) - glaciology
1842-1846 Nomenclator Zoologicus, a classification list of zoological genera and groups

Paleobotany (古植物学)

Late 19 c: Advance in Europe (esp., German) → established
Early 20 c: Advance the techniques of microscope and thin section → introduced to Japan

Paleobotany = botany + geology

  1. clarifying flora, distribution, vegetation, and the succession
  2. analyzing paleoecology and paleoclimate
  3. confirming phylogeny → plate tectonics (background)

[ era | chronology | extinction event | fossil 化石 ]

major Subjects
  1. Precambrian (先カンブリア) = beginning of life on earth
  2. Beginning of terrestrial plants = evolution of terrestrial plants
  3. Evolution of seed plants (esp., angiosperms)
The evoltion of plants and plants does not always occur together. In gereranl, plants evolve slightly earlier than animals, probably because of food chains.

Era ()

The Geologic Time Scale is an artificial division of the continuous history of the planet. Divisions are based mainly on changes in life. Divisions between Periods are often associated with major events such as extinction.
The boundaries are real places to geologists. The Proterozoic-Cambrian boundary is marked at a remote spot in a cliff face on the Burin Peninsula, Newfoundland where the change in fossil life marks the beginning of the Cambrian. It is placed between the appearance of the Ediacaran fauna and the first appearance of trilobites. Within this time span of 30-50 million years, the boundary is recognized by the appearance of small shelly fossils. Other fossil markers include the first appearance of worm tubes, called sabelliditids, various kinds of trace fossils and the later appearance of trilobites.

(St John Museum. Sept 19 2014)

Cryptozoic time (隠生代) = Hadean + Archaean + Proterozoic
Hadean (冥王代)
Arcaheozoic (始生代)
Proterozoic (原生代)
Phanerozoic time (顕生代) = Paleozoic + Mesozoic + Cainozoic
Cainozoic (新生代)
Mesozoic (中生代)
Paleozoic (古生代)
Chronology (年代学)

Cainozoic (新生代)

(Ellis 2018)

Anthropocene (人新世)
relating to or denoting the current geological age, viewed as the period during which human activity has been the dominant influence on climate and the environment

Etymology: anthropo- (Gr. human) + -cene (Gr. new or recent)

Table. Potential Anthropocene beginning with proposed GSSP markers
  • Extending farming, -11000 to 6000 yr BP: -8000 yr BP, CO2 minima in glacier ice
  • Rice production, -6000 to 3000 yr BP: 5020 BP CH4 minima in glacier ice
  • Columbian exchange (Orbis), 1942-1610: 1610 CO2 minima in glacier ice
  • The great acceleration, 1945-1964: radionuclides (1964 14C and 239Pu peak)
2009 Anthropocene Working Group (AWG) established in IUGS
2016 AWG: The great acceleration = beginning of Anthropocene

Quaternary (第四紀)

> 65 million-present
Holocene (完新世): 0.0117–0 (Ma)

[Jomon forest, Jomon man]

Jomon marine transgression (縄文海進)
7000-4000 YBP (peak = 6500-600 YBP)
= Holocene glacial retreat
Warm period (1-2°C > at present) → 2-3 m a.s.l. > at present
Pleistocene (更新世) 0.0117–2.58
Tarantian (タランチアン) 0.126–0.0117
Ionian (イオニアン) 0.781–0.126
Calabrian (カラブリアン) 1.80–0.781 Mya (± 5 Kya)

Upper boudnary: magnetic pole reversal (781 ± 5 Ka)
→ starting an ice age with global drying

Gelasian (ゲラシアン): 2.58–1.80 Mya

Lower boundary: extinct haptophytes (ハプト藻), Discoaster pentaradiatus and D. surculus

Fig. Sunda and Sahul. Ice age = 70000-14000 BP
Beringia (Bering land bridge, ベーリンジア/ベーリング陸橋)
Fig. Large scale biogeographic patterns in Beringia with the maximum extent of the Bering Land Bridge during the Last Glaciation (18000-15000 years ago) showing in yellow (modified from Elias and Crocker 2008) glacier
Fig. Minimum (interglacial, black) and maximum (glacial, grey) glaciation of the northern hemisphere during the Quaternary climatic cycles (18000-15000 years ago)

Tertiary (第三紀), 64.3-2.6 Mya

Neogene (新第三紀), 23.0-2.6 Mya
Pliocene (鮮新世) 5-2.58 Mya
Miocene (中新世) 23-5 Mya
Paleogene (古第三紀), 66-23 Mya
The age of mammals (哺乳類)
Oligocene (漸新世) 34-23 Mya
Chattian 28.1-28.93 Mya
Rupelian 33.9-28.1 Mya Eocene (始新世), 55-38 Mya
Priabonian 37.71-33.9 Mya
Bartonian 41.2-37.71 Mya
Lutetian 47.8-41.2 Mya
Ypresian 56.0–47.8 Mya
Palaeocene (暁新世) 66-56 Mya
Danian 66-61.6 Mya
Selandian 61.6-59.2 Mya
Thanetian 59.2-56.0

1874 Sclater, Philip Lutley: proposed Lemuria (Limuria)

lemur fossils in Madagascar and the Indian continent but not in Africa or the Middle East - Lemuria made the bridge between Madagascar and India
→ sank beneath the Indian Ocean
- rejected by continental drift theory

Mesozoic (中生代)

Gondwana·Laurasia [200 Mya] (Wegener 1912)
Gondwana layer in India: lime layer and mud-sand layer

Plant fossils: woody ferns (Glossopteris, Gangamopteris)

gneissic (片麻岩) and granite

250-65 million
Cretaceous (白亜紀)
Cretaceous–Paleogene boundary
145-65 Mya
warm climate → high eustatic sea levels
Jurassic (ジュラ紀)
Triassic (三畳紀): 2.51-1.95 Bya
Salzburg Salz (salt) - red sandstone
Tethys Sea (テチス海)
= Tethys Ocean or Neo-Tethys
started the development in late Devonian (Paleozoic)
prehistoric ocean during the Mesozoic Era and early Cenozoic Era, located between the ancient continents of Gondwana and Laurasia

Paleozoic (古生代)

Caledonian orogeny (カレドニア造山運動): early Paleozoic
Variscan orogeny (バリスカン造山運動) = Hercynian orogeny
4-2 Bya (Carboniferous - Permian)

between Eurasia (Laurasia) and Gondwana

Pangea/Pangaea [230 Mya], Gr. pan + gaia
Permian - Triassic
Only one supercontinent: split, drift and breakup
Permian (二畳紀/ペルム紀): 299–252 Mya (million years ago)
The world was dominated by two continents, Pangaea and Siberia, surrounded by a global ocean, Panthalassa
Carboniferous (石炭紀): 3.67-2.89 Bya
Devonian (デボン紀): 419.2–358.9 Mya
Wenlockian Ludlovian

Kawauchi Series = Wenlockian + Ludlovian


Takainari Series

Eifelian 3.933-3.877 Bya
Givetian: 3.877-3.827 Bya
Frasnian: 3.827-3.722 Bya (upper Devonian)
Famennian 3.722-3.589 Bya

Tobigamori Series = Famennian + Frasnian

Silurian (シルリア紀): 443.8–419.2 Mya
= Gotlandian + Ordovician, or Gotlandian
Gotlandian (ゴトランド紀)
Ordovician (オルドビス紀): 485.4–443.8 Mya [extinction event]
Tremadocian (478.6-488.3 Mya)
Floian (471.8-478.6 Mya)
Dapingian (468.1-471.8 Mya)
Darriwilian (460.9-468.1 Mya)
Sandbian (455.8-460.9 Mya)
Katian (445.6-455.8 Mya)
Hirnantian (443.7-445.6 Mya)
Cambrian (カンブリア紀)
Sigillaria were important trees in the late Pennsylvanian forest. They were smaller than some of the other lycopods, growing about 20 to 30 meters tall. The bark of fossil Sigillaria is easy to recognize. Unlike the other common lycopod, Lepidodendron, leaf scars of Sigillaria appear to be arranged in vertical rows. All of the lycopod trees, except for Sigillaria, became extinct before the end of the Pennsylvanian Period.

(St John Museum, Sept 19 2014)

Lycopod trees like Lepidodendron dominated the lowlands during the Pennsylvanian Period. They were large, growing to more than 50 meters tall with a trunk 1 to 2 meters in diameter. The “root” system extended as far as 12 meters into the floor of the swamps where they grew. The bark of Lepidodendron-like trees is easy to recognize. The spiral, diamond-shaped pattern shows where leaves were attached to the trunk and brnaches.
Although the name Lepidodendron is used for the entire tree. The parts of large trees are usually found separated from other parts of the tree. Detached roots, leaves, cones and spores have all been given separate names. Detached roots are known by the name Stigmaria. These fossils are often found in clay, believed to be soil in which the trees grew. The overlying coal layer represents the decayed and compressed swamp vegetation. Detached leaves are sometimes called Cyperites, while cones are known as Lepidostrobus.

(St John Museum, Sept 19 2014)

The most important swamp trees were lycopods, Lepidodendron and Sigillaria. Today lycopods in New Brunswick are represented by tiny plants, but more than 300 million years ago Lepidodendron grew more than 50 meters tall. During most of the Pennsylvanian Period Lepidodendron-like trees made up eighty percent of the forest. As the Earth’s climate swung from wet to dry, the forest composition changed too. During a second dry interval in the late Pennsylvanian most of the lycopods became extinct, and were replaced by ferns.
Coal deposits, characterized the Pennsylvanian Period, deposited mostly in lowland swamps where fallen tree trunks accumulated in large numbers. Fossilized roots of Lepidodendron are often found in clay soils, believed to have been the bottom of the Pennsylvanian swamps. Overlying coals represent the decayed and compressed swamp vegetation. Some layers even show evidence of ancient forest fires (森林火災).

(St John Museum, Sept 19 2014)

Proterozoic (原生代)

Least fossils - difficulties in aging
Rocks aged by potassium argon dating method and rubidium strontium dating method

the distribution of ages is discontinous - intermittency of earth crust movement and orogenesis


2.5 Bya-542 Mya
just before the proliferation of complex life on Earth
1.9 Bya: first birth of continent

Nuna/Neuna (= North Europe and North America)

1.8-1.5 Bya: Columbia Continent (= Hudsonland)

Fig. Columbia ≈ 1.59 Bya (Evans & Mitchell 2011, Pesonen et al. 2012, Zhang et al 2012). TS = transscandinavian igneous belt. YM = Yavapai-mazatzal. RN = Rio Negro-Jurena. 1380-1350. 1600-1300. Presumptive subduction. Columbia 1.59 Bya. Sedimentary Basins, 1.8-1.0 Bya. Mountain range formations, 1.66-1.50 Bya. Crations older than 2.3 Bya.

1.5-1.0 Bya Pannotia Continent

1981 McWilliams: proposed
1984 Bond et al.: developed in 625-550 Mya

1.0-0.75 Bya: Rodinia

1991 Hoffman: proposed

Archaean, or Arcaheozoic (始生代)

3.8(4.0)-2.5 Bya
the Earth crust had cooled enough to allow the formation of continents
2.5 Bya (late Archaean): Kenoran orogenic movement (= formerly Algoman diastrophism)
Fig. North America craton consists of a shield, where Precambrian rock is exposed, and a platform, where Paleozoic sedimentary rock covers the Precambrian

Hadean (冥王代)

= Pre-archean and Priscoan
The birth of earth to 3.8 billion

Planetary sicence (惑星科学)

≈ astronomy

The origin of the universe

Fig. Timeline of the metric expansion of space, where space (including hypothetical non-observable portions of the universe) is represented at each time by the circular sections. On the left, the dramatic expansion occurs in the inflationary epoch; and at the center, the expansion accelerates
Big bang theory, BB theory (ビッグバン理論)
All of the current and past matter in the universe came into existence at ≈ 13.8 billion years ago

(Sato 1981, Guth 1980)

Inflationary universe theory (インフレ宇宙論)

Astrobiology (宇宙生物学)

Fermi paradox (フェルミのパラドクス)
Drake equation (ドレイク方程式)
a probabilistic equation to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy

N = R*·fp·ne·fl·fi·fc·L

N = the number of civilizations in our galaxy with which communication might be possible
R* = the average rate of star formation in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of planets that could support life that actually develop life at some point
fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space

R* ≈ 1-10 year-1
fp = 0.5 (tentative)
ne = 1 (e.g., the solar system has Earth = 1)
fl, fi and fc = 1, respectively (optimistic assumption)
L = not determined (controversial)

L is the most important factor to determine N

When L = 1 million years, N = 5 million

The solar system (太陽系)

Def. Planet (惑星): an extremely large, round mass of rock and metal, such as Earth, or of gas, such as Jupiter, that moves in a circular path around the sun or another star
Def. Meteorites (隕石): a piece of rock or other matter from space that has landed on earth
Records of meteorites (隕石の記録)
2013.09:20 (YEKT): Chelyabinsk meteor stroke Ural region
2008.10.07 TC3 stroke Nubian Desert in Sudan
1908 Tunguska explosion (event)
≈ BC660 Kaali craters on Saaremaa Island in Estonia
2.8 mya Kebira Crater
65.5 mya Chicxulub crater in Yucatan Peninsula, Mexico
65.5 mya Shiva crater (trace of asteroid impact) - doubtful
2.51 bya Wilkes Land crater in Antarctic
element Fig. Abundance (atom fraction) of the chemical elements in Earth upper continental crust as a function of atomic number. The rarest elements in the crust (shown in yellow) are rare due to a combination of factors: all but one are the densest siderophiles (iron-loving) elements in the Goldschmidt classification, meaning they have a tendency to mix well with metallic iron, depleting them by being relocated deeper into the Earth core. Their abundance in meteoroids is higher. Tellurium has been depleted by preaccretional sorting in the nebula via formation of volatile hydrogen telluride.

Open earth (開かれた地球)

Palaeomagnetism or paleomagnetism (古地磁気)

Study on magnetic fields recorded in rocks, sediment or geophysial materials

support the continental drift based on plate tectonics

1906 Brunhes, Bernard 1867-1910, France: discovered paleomagnetism

some rocks had magnetic properties that were the exact opposite as the Earth magnetic field →
Earth magnetic field has reversed from time to time

1929 Matsuyama (松山基範) 1884-1958: the reverse of magnetic field

young rocks = straight polarity ↔ old rocks = reversed polarity

≥ 1950: reversed paleomagnetism supported by lava stratigraphy in Iceland
≥ 1960: measurements of paleomagnetism for the past 4 Mya

in volcanic rocks worldwide, combined with K-Ar dating
chron (former epoch, = four chrons) → subchron (former event)

paleomagnetism                    ↑ Matuyama–Brunhes polarity transition
Fig. Temporal changes in paleomagnetism for the last 6 million years (Gee & Kent 2007). Black and white indicate the direction is same with the present (straight polarity or normal) and not (reversed polarity or reverse), respectively.

paleomagnetism reversal occurred a few hundreds of times - coded by number

≥ 1960: Vine–Matthews–Morley hypothesis

When geomagnetic reversal and seafloor spreading are assumed, oceanic stripe magnetic anomalies can be explained
= supported plate techtonics

Earth interior (地球内部)

Classification by components:
Shallow ⇐ earth crust (地殻), mantle (マントル). core (核) ⇒ deep

Earth crust (or crust, 地殻)

Oceanic crust: made of basalt

low silica and high in Fe and Mg - high density

Continental crust: made of granite

high Al and Mg silicate with quartz and feldspar - low density

⇒ Continents lie above sea leavel and oceanic crust lies below sea level due to the density differences

Mantle (マントル)

Core (核)

Outer core (外核)
Inner core (内核)

Origin of sea (海の起源)

Earth is suitable location to allow water to be in liquid state
the ocean covers 71% of the earth surfae, containing 97% of the water on the earth

covers 61% of the northern hemisphere and 80% of the southern hemisphere

Big bang → galaxies and stars → solar system →

the earth (core + mantle + crust)

Probably the oceans formed as soon as the earth cooled enough for water to become liquid

≈ 4 bya (∵ the oldest rocks = 3.8 bya)

Outgassing (気体放出): oceans are byproducts of heating and differentiation

water locked in the minerals as hydrogen, as earth warmed and partially melted, and oxygen was released and carried to the surface by volcanic venting activity

Sea salts: chemicals leached from the rocks in the crust + some volatile chemicals (hydrochloric acid and hydrogen sulfide) released from the earth interior by volcanic activities

probbly the ocean became salty soon after it formed. Salts have accumulated gradually due to weathering

Chronology (年代学)

Etymology: chronos (Gr. χρóνς, time) + (Gr. -logica, λογíα, logics)
Definition: the determination of the temporal sequence of past events

chronology of planets
chronology of succession
chronology of volcanic eruptions
chronology of seedbank

Potassium argon dating (K-Ar dating, カリウム-アルゴン法)
Rubidium strontium dating (Rb-Sr dating, ルビジウム・ストロンチウム法)
Carbon 14 dating (炭素年代測定)

Direct measurement of seedbank age

Abstract. We describe a new approach to determining the age structure of seed banks of natural plant populations and apply it to a natural population of the Sonoran Desert winter annual, Pectocarya recurvata (Boraginaceae). Unlike other 14C techniques, tandem accelerator mass spectrometry (TAMS) counts the number of carbon isotope atoms, permitting high precision with small samples. Aboveground nuclear bomb tests caused atmospheric 14C levels to peak in 1963. Their subsequent gradual decline provides a signal for aging seed banks with TAMS. We constructed a calibration curve using seeds with known dates of production during 1980.1995, then used it to age 53 seeds sampled from a natural seed bank in 1993, at the Desert Laboratory in Tucson, Arizona. Seed number declined with age at an approximately exponential rate, with the oldest recovered seed having an estimated age of 5 yr (95% CI = ± 2.3 yr). The seed bank age structure was judged more than adequate to buffer this population from typical fluctuations, based on an examination of 15 yr of population dynamic data. The TAMS technique has strong potential for answering a broad range of ecological and evolutionary questions requiring post-1963 age determinations and for which a several-year confidence interval is acceptable.

(Moriuchi et al. 2000)