Final Project Text Accompaniment
I have researched the major geologic events for the past 800 million years that helped create the Pacific Northwest and translated it into a linear illustration that follows the geologic timeline. My intended audience is students of middle school level or higher. It began as sketches in my notes as an attempt to understand the material through a visual path. I wanted to place the events sequentially, so I could understand what process had come before and how it lead to events that followed. I’ve also added information about climates, sea levels, and organisms because I think it helps give depth and a better “sense” of what time periods the geologic events also take place. I hope other students who are visual people like me may find it helpful to grasp the scale and timing of the events that created the Northwest.
How to Read the Illustrations:
On purpose, I didn’t add a key or a legend to go along with it. This project wasn’t intended as a map but rather I wanted to illustrate the relationships between time periods. I also wanted people to be able to appreciate it simply as a piece of art. That being said, there is a definite logic behind what I drew.
Each panel as three sections: top, middle, and bottom. The top has the name of the epoch or time period, the middle contains the illustration, and the bottom has a continuous time scale. Each panel measures the events of 100 million years. Every 50 million years is marked numerically. Each dot marks 10 million years. Because of sizing and artistic balance, some illustrated events might venture beyond its strict age.
When bound by its ring, the project can be read as a book. Unbound, it can be stretched out, like an accordion, so one might interpret the events in the entirety of an 800 million scale – which is how I prefer the reader to see it.
The blue orbs that appear three or four times throughout are a rough map of the planet at that time. This helps the reader keep in mind that though he/she is seeing a mountain range illustrated, the reality is that everything, globally, is shifting and changing.
When in a period of warm climate, clouds appear over the mountains and the sea water becomes a lighter colour, and the scene more cheerful. During glacial periods, the mountains are jagged, capped with ice and the entire scene is slightly more monochromatic. If there are no mountains, white whisps that look like cirroculumous’ (cold weather clouds) appear. The great extinction at the end of the Triassic period is indicated by the mood of the sea – rough and tumultuous.
The Information in Each Set of Panels:
Proterozoic: Pages 1 and 2
A blue map of the Earth at that time shows Rodinia as it prepares to rift. We see brown island and a rock in the middle of the double-spread that drifts further away as we move right, indicating this rift. A small inland sea forms between the two islands and we see arrows showing sediments collecting in this small inland sea. This is the Windermere Formation we see forming.
Most of the time leading up to the Cambrian epoch was glacial climate. The Toby and Monk Formation are from this time. We see glacial till preserved in these. Sea level is relatively low. Organisms are few and basic – like algae. Complex life we know it comes later. As we move right and towards the Cambrian age, the colours of the mountains become more brown and warmer. We are moving out of the glacial period.
Cambrian, Ordovician, Silurian: Pages 3 and 4
As the glacial age ends, the Cambrian epoch begins with the spectacular Cambrian Explosion – and explosion of diverse and complex life forms evolving rapidly. This is shown by the pink circle overlaid with the early worm, leafy plants, early fish, the ancestor of the horse-shoe crab and plankton. Now we are in a tropical climate with rising sea levels.
To the right of this illustration is a sandy landmass, which represents the Sauk Formtion – one of several that are laid down in the next few periods. The sea level rose and fell at least 4 times in the next 4 epochs, and each time the sea level changed, it left an unconformity between such formations as Sauk and the Tippecanoe. In the late Ordovician epoch we see the ancestor of the starfish appear, after which sea levels drop. The Appalachians, once an island arc, accrete at about this time on the East coast. We pass through a short glacial age.
Devonian, Permian, Triassic, Jurassic: Pages 5 and 6
We enter a period of relative tectonic quiet in the Northwest. The organic history is more exciting at this point. It is mostly a warm climate with diverse marine life forms developing stiff lower jaws and softer bodies – much more like our modern-day fish. The Kootnay Arc is deposited as the Kootnay volcanoes erupt to lay down a volcanic layer which will later be met by the Inter-Montaine Superterrane many millions of years later. The first modern tree, the Archaeopteris appears in the mid/late Devonian period. Sea levels drop then rise again. The ancestor of the modern shark appears. The earth is abundant with corals. The blue spheres show Pangea breaking apart and coming back together, which is does continually in the next 150 million years. Elsewhere, landmasses are interacting, but not so in the Northwest. A glacial period and great extinction ends the Triassic period, wiping out 95% of all life. This is shown by the snowy mountains and stormy sea.
Cretaceous, Tertiary, Quaternary: Pages 7 and 8
The last 200 million years is when the Northwest starts forming and it does so rather quickly and in complex ways.
As we start in the Cretaceous epoch, we see the Inter-Montaine being accreted onto the continent, creating a subduction zone with subduction volcanoes. To the right, from top to bottom, we see the Farallon plate approaching. It is preceded by Wrangellia. As it gets closer, we see two or three other green and yellow small masses being pushed in front of it. These the micro-terranes of the North Cascades. At the end of page 7 we see it accreted on obliquely in long, squashed blobs.
As sea levels rise in page 8, we see the Farallon plate carrying its island arc and splitting into the Kula and Farallon. Just before it reaches, we see the Okanogan hot spots. As it finally accretes, we see the Peripheral rocks being folded and the ocean crust being scraped and packed on the other side of its folds. The Kula and Farallon plates disappear after this as it has been subducted underneath.
Finally, sea levels rise and we enter the glacial period we are now in. A glacier shows how the most recent geologic history of the Northwest was due to glaciers. It is carving out valleys and leaving streams of till and sediment. At the right of the glacier, it has cut a path to the sea. This is meant to refer to how the Puget Sound was changed from fresh to salt water, after glaciers connected the inland streams to the sea.
Page 9
We end with a map of the modern globe.
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