Over millions of years, microscopic marine plants and animals that lived in an ancient sea covering Oklahoma died and sank to the ocean floor. Sediment gradually buried them, subjecting the remains to intense heat and pressure over time. This transformed the organic material into oil and natural gas trapped within sedimentary rock formations. Today, these fossil fuels are extracted from 71 of Oklahoma's 77 counties.

1. Cooking Up Crude
Formation of Oil and Natural Gas

2. How did crude oil and
natural gas form?
 Concept: The oil and
natural gas taken from the
earth’s crust today
originated as microscopic
plants and animals that lived
in the ocean millions of
years ago.

3. You will need:
Paper
Pencils
Map pencils, crayons, or
markers

4. Make space on your table
to draw.
Fold your paper into three
equal sections by drawing
two lines across the width
of the paper.

5. Label
Label the sections:
Scene One, Scene
Two and Scene
Three.

6. History of Formation of
Oil and Natural Gas
I am going to tell you a
story about the history of
the formation of oil and
natural gas in Oklahoma.

7. Draw a picture of what
you hear.
 570million years ago-during a period
known as the “Paleozoic Era” a large
sea covered the area we now call
Oklahoma. In this sea lived a vast
number of microscopic plants and
animals called plankton. This
microscopic plankton drifted on or
near the surface of the water and
became so numerous that it could
actually be seen with the naked
eye.

8. Real Plankton

9. Cartoon Plankton

10. Paleozoic Era Sea
 Throughout the “Paleozoic Era” the sea was also
alive with trilobites, corals, crinoids, brachiopods
and many other plants and animals which evolved
over millions of years.
 A trilobite was a strange-looking little creature. Small
grooves divided its body and hard segmented shell
into three vertical parts. Its head was covered by a
semicircular shield.

11. Trilobite

12. Coral
 Coral, which still exists today, came in many
different sizes, shapes and colors. The coral polyps
were simple animals that were able to take calcium
out of saltwater and convert it into a rocklike shelter,
in which they lived.

13. Crinoids
 Crinoids anchored themselves to rocks on the sea
floor with a root-like structure that supported a stalk
or column topped by a cup-like cavity, which formed
a protective case for a flower.

14. Brachiopods
 Brachiopods were clam-like animals. Their two-piece
dorsal and ventral shells enclosed and protected their
soft body parts.

15. Wichita and Arbuckle
Mountains of Oklahoma
 During this same time period, there was a great
mountain range much like the Colorado Rockies,
which ran along the edge of the sea. It was one of the
tallest mountain ranges on earth and was actually
connected to the Rockies. Today we call these
ancient mountains the Wichita and Arbuckle
Mountains of Oklahoma.

16. South Mountain, Wichita
Mountains, Oklahoma

17. Turner Falls, Arbuckle
Mountains, Oklahoma

18. Sediments ended up in the
sea with the creatures.
 As the wind, rain, avalanches and ice movements
eroded the Wichita and Arbuckle Mountains, tiny
particles—called sediments—were carried into the
sea where the billions of tiny sea creatures lived.
Wind and rain also carried sediments from other
parts of the world.

19. Layers of Sedimentary
Rock

20. I suddenly have a sinking
feeling.

21. Plankton and other sea life
died and sank.
 Due to their ability to reproduce quickly, the
plankton, along with other sea life, were abundant.
As these carbon–containing organisms went through
their extremely short life cycles and died, their
remains sank to the deep sea floor and became
covered with the mud, sand and sediment from the
eroding mountains and surrounding areas. Because
they were buried so quickly on the deep sea floor, the
plankton and other sea creatures lacked oxygen,
which is necessary for decay (or decomposition).

22. Can you picture this scene?
 Now it is your turn. Draw
scene 1: Oklahoma’s Wichita
and Arbuckle Mountains
partially covered by a sea
containing plankton and
other sea creatures.

23. Chapter 2
 320 million years passed, and the layers of sediment
on the sea floor became thousands upon thousands
of feet deep. These layers were filled with dead
plankton, fossilized sea creatures and eroded rock!

24. Mesozoic Era
 During this time period—known as
the “Mesozoic Era”—dinosaurs
began to roam the earth and swim in
the sea. More than half of the great
sea had disappeared because of
evaporation, earthquakes, and the
filling and layering of sediments on
the sea floor.

25. Plesiosaurs

26.  The mountain range was significantly smaller
because of millions of years of erosion. The
continued accumulation of sediments in the sea
buried the organic-rich layers deeper and deeper,
creating immense heat and pressure.
 This heat and pressure was responsible for changing
the dead organic material into hydrocarbons
(substances containing hydrogen and carbon)
causing the remaining inorganic material to change
into sedimentary rock.
 Can you picture this scene?

27. Organic material became
hydrocarbons.

28. Picture scene 2.
 This heat and pressure was responsible for changing
the dead organic material into hydrocarbons
(substances containing hydrogen and carbon)
causing the remaining inorganic material to change
into sedimentary rock.
 Can you picture this scene?

29. Scene 2 pictures.

30. Cenozoic Era
250 Millions years later brings us to present day- the
“Cenozoic Era”. Man now walks the earth and the
dinosaurs have long since disappeared. The erosion
from the mountains and other sediments have now
completely filled the great Oklahoma Sea. The
Wichita and Arbuckle mountain ranges are much
smaller and no longer connected to the Rockies, or
each other. Shifts in the earth’s surface have also
affected the size of the sea and mountains over these
millions of years.

31. Eroded Wichita
Mountains

32. Creating Oil and Natural
Gas
 The heat and pressure have formed many layers of
sedimentary rock, and deep source rock (rock where oil
and natural gas form). Much of the water that was in
the sea is now in the pore spaces of the sedimentary
rock. The remaining water evaporated or was pushed
into areas where seas or oceans now exist.
 Over millions of years, temperatures ranging from 150-
300 degrees Fahrenheit have cooked the organic
materials causing a complex chemical change, creating
hydrocarbons called oil and natural gas. These
hydrocarbons, also known as fossil fuels, have been
produced in 71 of Oklahoma’s 77 counties.

33. Draw scene 3.

34. Communicate
 Using the pictures you have
drawn, tell how oil and natural
gas are formed.

35. Summary
 Much of what is Oklahoma today was under an
ancient ocean millions of years ago. Geologists
believe this because many rock layers containing
fossil remains of marine life have been found
throughout the state. Millions of microscopic
marine plants and animals which lived in the waters
eventually died and settled on the ocean floor. The
dead plants and animals were often buried by sand
and other sediment. Heat from beneath the earth’s
crust “cooked” the plant and animal remains
forming oil and natural gas deposits within the rock
layers. This is why oil and natural gas, or petroleum,
are called fossil fuels.