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169

Era

Period

Cenozoic

Quaternary

Epoch Holocene Pleistocene

Today

7,645 Years Ago: Age of Volcanic Activity Core

Pliocene Miocene Tertiary

Oligocene Eocene Paleocene

Mesozoic

Cretaceous

Late Early Late

Jurassic

Middle Early

206 Million Years Ago


Volcanic Activity This core was taken from the Saanich Inlet, a fjord in southeastern Vancouver Island, 25 km north of Victoria, British Columbia. It records exciting events taking place during our recent Earth’s history.

Varve Layer

oldest

This layer is made up of varves. A varve is an annual layer of sediment, (like a yearly growth ring on trees). The light layers were deposited during the summer. They are full of diatoms that grow and bloom during spring and summer.

f varve s.

The darker layers were deposited during the winter. It is silt, without diatoms, from a the nearby Cowichan River.

le o

1

youngest

Does this whitish color remind you of anything? It’s ash! The ash in this layer comes from the eruption of Mt. Mazama in Oregon 7,645 years ago. The eruption caused ash to cover large parts of the Pacific Northwest and Canada, and resulted in the formation of Crater Lake.

mp

2

Ash Layer

An

ex

a

Leg 169-1034D-7H-1A


208

Era

Period

Cenozoic

Quaternary

Epoch Holocene

Today

Pleistocene Pliocene Miocene

Tertiary

Oligocene Eocene Paleocene

Mesozoic

Cretaceous

Late

55 Million Years Ago: Age of Climate Change Core

Early Late

Jurassic

Middle Early

206 Million Years Ago


Climate Change Your core tells the story of a time in Earth’s history when, over a period of 20,000 years, temperatures all over the planet increased by 6°C (11°F). The evidence in this core suggests that the rapid increase in temperature was caused by gasses that were released from the ocean floor.

2 1

youngest

Where did the fossils go? The methane released into the atmosphere dissolved in the oceans making the seawater more acidic. This caused the calcium carbonate shells of the planktonic microfossils to dissolve. This layer is mostly made of clay particles.

At the boundary Around 55 million years ago, approximately 2,500 billion tons of carbon in the form of methane gas were released rapidly into the ocean and atmosphere. This release was caused by a warming event at the bottom of the ocean. The dramatic line in the core reflects the dramatic change that took place on Earth.

Paleocene Layer This layer is made up of thousands and thousands of fossils from single-celled organisms that thrived in the ocean over 55 million years ago. At the time, the ocean temperature was 12 - 16°C (53 - 60°F). The layer is white because the shells are made of a white mineral called calcium carbonate.

oldest os ca r b o il s sil c na fo s s lu b . t e m i c r o org

3

Eocene Layer

m ciu C a l // n cf : h tt p

Leg 208 -1262B-15H-3


171

Era

Period

Cenozoic

Quaternary

Epoch Holocene

Today

Pleistocene Pliocene Miocene

Tertiary

Oligocene Eocene Paleocene

Mesozoic

Cretaceous

Late Early

65 Million Years Ago: Age of Mass Extinction Core

Late Jurassic

Middle Early

206 Million Years Ago


Mass Extinction This core shows volcanic activity that took place in the late Cenozoic about 9 million years ago. Compare the size and the types of microfossils found in this layer to those in the older bottom layer. Many different types of forams became extinct after the impact, just like the dinosaurs and other organisms. ers

4

youngest

Tertiary Layer

n if

i

1

Ash Layer Does this orange/reddish color remind you of anything? It is the ash and dust that fell to earth after the meteor hit.

kti

These are tiny glass-like rocks called microtektites. The meteor hit with such great force that it caused tons of super heated rock and other debris to fly high into the sky then rapidly cool to form fine glassy particles. What rained back down onto Earth formed this layer.

te s

Tektite Layer

M ic

r ot

e

oldest

Cretaceous Layer During the time of the dinosaurs, lots of different types of organisms called foraminifers (forams for short) lived in the ocean. When they died, their shells settled to the bottom of the ocean and over time became fossils. This layer shows how many different sizes and types of these organisms existed.

ers

2

am

i

n if

3

F or

F or

am

Leg 171B-1049A-17X2



Core Indentification Guide