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Core Identification Guide
169
Era Period Epoch
Cen
ozoi
c
QuaternaryHolocene
Pleistocene
Tertiary
Pliocene
Miocene
Oligocene
Eocene
Paleocene
Mes
ozoi
c
CretaceousLate
Early
Jurassic
Late
Middle
Early
Today
206 Million Years Ago
7,645 Years Ago: Age of Volcanic Activity Core
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.
Volcanic ActivityThis 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.
The darker layers were deposited during the winter. It is silt, without diatoms, from a the nearby Cowichan River.
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.
Ash Layer youngest
oldestVarve Layer
An example o
f var
ves.
1
2
Leg 169-1034D-7H-1A
208
Era Period Epoch
Cen
ozoi
c
QuaternaryHolocene
Pleistocene
Tertiary
Pliocene
Miocene
Oligocene
Eocene
Paleocene
Mes
ozoi
c
CretaceousLate
Early
Jurassic
Late
Middle
Early
Today
206 Million Years Ago
55 Million Years Ago: Age of Climate Change Core
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.
At the boundary
Climate ChangeYour 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.
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.
Paleocene Layer
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.
Eocene Layer
Leg 208 -1262B-15H-3
Calcium carb
onat
e m
icro
foss
ils
http://ncfo
ssilc
lub.
org
1
3
2
youngest
oldest
171
Era Period Epoch
Cen
ozoi
c
QuaternaryHolocene
Pleistocene
Tertiary
Pliocene
Miocene
Oligocene
Eocene
Paleocene
Mes
ozoi
c
CretaceousLate
Early
Jurassic
Late
Middle
Early
Today
206 Million Years Ago
65 Million Years Ago: Age of Mass Extinction Core
Mass ExtinctionThis core shows volcanic activity that took place in the late Cenozoic about 9 million years ago.
Leg 171B-1049A-17X2
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.
Tektite 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.
Cretaceous Layer
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.
Tertiary Layer
Does this orange/reddish color remind you of anything? It is the ash and dust that fell to earth after the meteor hit.
Ash Layer
Foraminife
rs
Microtektite
s
Foraminife
rs
1
2
3
4 youngest
oldest
