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Before First Contact - Geology, Part one

6/30/2015

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PictureThis figure shows a calculation for thermal convection in the Earth's mantle. Colors closer to red are hot areas and colors closer to blue are cold areas. A hot, less-dense lower boundary layer sends plumes of hot material upwards, and likewise, cold material from the top moves downwards. - Wikipedia
“Differentiation” is a term that has a little to do with geology, and a little with cosmology. In space, a giant ball of molten rock has a lot of convection going on inside, where heavier elements sink to the middle of the ball and stay molten due to the pressure, while lighter elements rise to the surface and cool at a faster rate. Differentiation is what created the Earth's core, mantle, and crust. As the Earth's cooled crust sat on top of a thick layer of flowing rock, the surface started to crack, dividing the crust into several tectonic plates that glide across the surface of the mantle from the convection it creates. These plates will eventually arrange themselves into several super continents that will break up and reform to make the continents we see today.

PictureMiddle Triassic Period, 250 million years ago. - Google Earth
After many face changes over billions of years, hundreds of millions of years ago, all of the tectonic plates were joined into one large landmass, called Pangaea. One of these plates making up Pangaea, the North American Plate, was in the Midwestern corner of the super-continent, and the Pacific Plate was just a micro plate south of the enormous Farallon Plate. In time, convection caused volcanic activity that influenced the growth of  the Pacific Plate. The growth of the Pacific Place pushed the Farallon Plate aside towards the west, which in turn, pushed up arcs of volcanic islands through the water at its edges. These islands drifted westward, before crashing into the north western corner of the North American Plate, breaking off from the Farallon, and forming the lands of Guatemala, Chipas, Oaxaca, Veracruz, Tlaxcala, Morelos, Guerrero, Mexico, Hidalgo, Michoacan, Queretaro, Guanajuato, Colima, Jalisco, Nayarit, Aguascalientes, San Luis Potosi, Zacatecas, Tamaulipas, Sinaloa, Durango, Nuevo Leon, Coahuila, Chihuahua, Sonora, Baja California, and Baja California Sur. The formation continues up to Arizona, New Mexico, Colorado, Wyoming, and Montana, up through Canada's Alberta, Northwest and Yukon territories as well as Alaska. Then south to the lands of British Colombia, Washington, Oregon and Upper California, which looked very different as the land was flatter than it is today.

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Late Triassic, 220 million years ago. The thin strips of land are being pushed into the continent, creating the future western lands of North America. - Google Earth
About 200 million years ago, a fault line appeared between the area of land that is now called "New Jersey" and the land that is now called "Morocco", marking the breakup of Pangaea and over time, the rift between the two lands separated more and more, eventually filling with water and giving birth to oceans: First the Tethys, then the Atlantic.
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Early Jurassic, 200 million years ago. As more land is being added to continent, it begins to break up. - Google Earth
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Middle Jurassic, 170 million years ago. The formation of the western lands of North America continue with the addition of Wrangellia, while the Atlantic Ocean continues to form. - Google Earth
Picture Late Cretaceous, 90 million years ago. - Google Earth
While Pangaea was beginning to break up, the Triassic/Jurassic extinction event occurred. Though we don’t know how it occurred, the most reasonable explanation was some form of climate change. This eventually allowed the first evolving dinosaurs to begin their reign on the planet. At this time, ocean levels rose, the climate became hot and muggy from pole to pole, and the landmass that San Diego would one day rest upon was still underwater. Zooming back out into the continents,  90 million years ago, the Midwest of the North American Plate was covered by an ancient sea, separating the arcs of land to the far west from the lands to the east. Over time, rain and snowfall in the mountain regions allowed ancient rivers and beach tides to slowly erode away the high peaks, and mud and sediment from this erosion would be carried downstream into the ancient Paleo-Pacific Ocean. This made deep ocean beds shallower and shallower, and the high mountains eroded away. As sea levels later fell, it slowly exposed the lands and joined the east to the west once again. To the west, as sea levels periodically changed, Precambrian Era sands crept further and further west, and were accumulating in sedimentary layers, fossilizing many ancient species in the process.

 The North American plate was drifting west, while the Farallon Plate, pushed by the growing Pacific micro plate, was moving east. Eventually, the Farallon Plate began to sink under the southwestern edge of the North American Plate, creating an off shore trench. The push also caused more underwater land between the trench and the coast to rise from the sea into a new arc of ancient volcanoes, which were actually the future eastern mountains of the Peninsular Region and Sierra Nevadas, and were much higher back at that time. The active volcanoes spread ash and sediment onto the Farallon Plate as it continued to dive underneath the North American Plate, deepening the trench, and heating the rocks under the land into granitic magmas, which were pushed up to the surface through the volcanoes. Mountain growth stopped about 90 million years ago, once the Farallon Plate was completely buried under the North American Plate, but volcanic activity didn't stop until about 28 million years ago, when subduction finally ended. These volcanoes probably became extinct at that time.
Rains and freeze/thaw cycles begin to take a toll on the rugged mountains of the Peninsular and the Sierra Nevadas, which began to get eroded by the rains. The land that would someday begin to form San Diego was born in the Jurassic Period, about 130 miles south-east of where San Diego presently lies, possibly close to where the Mexican city of San Luis Rio Colorado is today. About 75 million years ago, the sediment that eroded away from the Cuyamacca mountains was carried toward the Pacific by melting snow and rain waters. The stream cut a gorge through the Peninsular, creating a small delta that grew into a reletively flat coastal plane, and birthed the San Diego River. The land around the river then continued to be cut down to sea level. As sea levels rose and fell on the beaches, the sediments would layer up. Because the receding water was gradual, beaches would someday become inland Mesas.
Zooming back into the area, at the end of a Peninsula that stuck out of the middle north part of a large, ancient bay, is Cowles Mountain. It is the remnants of an ancient volcano separating future El Cajon and La Mesa, which were still submerged under water at that time.

K/T Boundary

PictureLate Cretaceous, 65 million years ago. - Google Earth
65 million years ago, in an area about 3000 km east from San Diego, a 10 km wide meteor or comet barreled into the present day Yucatán Peninsula, causing global destruction. Earthquakes, volcanic eruptions, and mega tsunamis ensued. The debris from the blast reached Earth’s atmosphere and as it rained back down, it became superheated before impacting the surface as fireballs. This also raised the temperature of the atmosphere, ignited mass wildfires, dropped sea levels which exposed more land, and ultimately triggered the Cretaceous-Paleogene extinction event. The land that was forming into San Diego, being as close as it was to ground zero, probably took a good brunt of fire and brimstone and suffered a drop in sea levels. When the dust finally settled, three out of four living things on the planet had died, including most of the dinosaurs. This left a thick layer of ash all over the world, which was later buried by sediment, and compacted into what geologists call the K-Pg Boundary.

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K-Pg Boundary rock. Contains a layer of Iridium that once blanketed the globe, but was then buried and fossilized. On Display at the San Diego Natural History Museum.
PictureEocene, 50 million years ago. - Google Earth
Back in San Diego, by about 50 Million years ago, a small system of rivers was beginning to form at this time which continued to deposit and distribute sediment into new land. One of the rivers up north was the Santa Ysebel which carved out San Pasqual Valley in the process of draining into the San Dieguito River, which carved  through the land before emptying into the Pacific Ocean. As the ocean levels continued to rise and fall, the sediment at the mouth of the San Dieguito River was pushed southward by winds and water currents, giving an initial shape to the curving coast and creating its first modern peninsula, later to be called Crown Point. Looking south of Crown Point, the sediments that flowed from the Cuyamacca Mountains, was forming the lowlands that will someday form Point Loma. Still influenced by the rise and fall of ocean levels, winds and currents, erosion on the coastal edges caused pieces of the raised land to fall off of the edges and sink into the ocean, further shaping the coast and creating the cliff edges of Del Mar, La Jolla, and Point Loma, these changes are still evident today. The southern portion however, was still underwater.

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San Pasqual Valley as it is today.
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My bad attempt at what San Diego may have looked like 50 million years ago.
By 30 million years ago, the Pacific and North American Plates finally met and started to grind, giving birth to the 800 mile long San Andreas Fault. This also bent the land upward to the west of the San Andreas Fault, but sunk the land where the fault was at, creating the future Salton Sink. Far to the west, where San Diego is, many other smaller faults were created in the process, like the Rose Canyon Fault, and the La Nacion Fault system. About 6 million years ago, because the Pacific Plate continued to grind north, the entire coast of California shifted up the same way, slowly tearing a rift valley between Baja-California and the Mexican mainland, which filled up with ocean water to become the Gulf of California. The ancient Gulf of California reached all the way up north to future Indio, California until ocean levels fell again.
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Oligocene, 35 million years ago. Notice that Baja California is still connected to the Mexican mainland. - Google Earth
Meanwhile, the Rose Canyon fault started to shift the northern coast of San Diego to the northwest. The shifting faults warped the coastal topography of San Diego, raising Mount Soledad and Point Loma high from the waters. The land to the east and south of Point Loma stayed underwater, making it an island and creating an enormous bay from La Jolla, down to Encinada, Mexico and reached as far east as La Mesa. The La Nacion Fault is actually a system of faults that lower in elevation as you move westward from the mountains to the beach where present day Chula Vista and National City sit. Those lands were still under this enormous ancient bay.
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Miocene, 20 million years ago. Notice the Baja Peninsula beginning to rip away. - Google Earth
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Holocene, 12 thousand years ago. Baja Peninsula will continue to move north. - Google Earth.
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An attempt to draw how San Diego looked 3 million years ago. Red lines are approximate fault lines that shaped San Diego.

Sources:

San Diego County Geological History
https://www.youtube.com/watch?v=FZp0i_hIkWM

The Rise and Fall of San Diego
https://www.youtube.com/watch?v=-drjJoRGfAk

Geologic Map of San Diego
http://www.quake.ca.gov/gmaps/RGM/sandiego/sandiego.html

From the San Diego Natural History Museum
https://www.sdnhm.org/archive/research/paleontology/sdgeol.html
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Tonight's Sky...

6/26/2015

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Setting so close, yet so far...

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Introduction

6/1/2015

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As I write this introduction, I’m standing at the end of Pacific Beach's long pier, watching the Earth turn, or as you like to call it, watching the Sun set. To my right, are the steep cliffs of La Jolla, and to my left is Mission Beach, bustling full of people, and Point Loma. In the distance to the south, you could barely see through the blue haze, one of the four Los Coronados islands. Behind me, the dim Moon in its waxing gibbous phase is just beginning to rise in the east. The breeze coming in from the west is cool, but not too cold, and the salty sea smell is energetic. As the earth rotates the American continent into darkness and the city lights begin to flicker on, I start to reflect on why I took this project on.

When it comes to thinking big, there is nothing like looking into the oblivion of the seemingly endless Pacific Ocean, named so for how calm and peaceful it is. The vista is so vast; you can slightly see the curvature of the Earth. I’ve lived here all my life and knew San Diego had a diverse history, but I never cared to take the time to learn about it. All of the history books and audio lectures I've consumed over the years never gave me the thrill that studying San Diego has, probably because the way I learned about the area’s history was much more practical than just reading a book or listening to a lecture. Here, I can actually visit the sites and have a better perspective of what the individuals I’ve read and heard about went through. It’s convinced me that more people should better understand their own local history in this way.


Though I will try to keep the story as simple to understand as possible, these stories are not simplistic. These stories are full of natural and human events, with all of its complexities, untold motives, and emotions that ultimately brought us all to the point we are at today. Hundreds of thousands of people have helped to develop San Diego into the metropolis that it is today, so there is a lot of context to cover. Real life dramas, featuring people who actually lived, loved, and left their mark, will be told. Some of these people are national figures while others have almost been forgotten. When people pass away in these stories, we will move on to the next story, but know that the people we read about, and their loved ones do not. This story is an amalgamation of many individual stories, chopped up and edited for your consumption.


San Diego’s history is usually divided into four eras, depending on who inhabited the area during that time: The Kumeyaay, Spanish, Mexican, and American eras. The American era is obviously the best documented, and we are still living it, so that should be fun to interpret! Much of these stories are influenced by pop culture of the past. For instance, faith was extremely influential during the time of Spanish reign, and many Spanish writers wrote faith based novels that would go on to inspire future generations to dream bigger. It is important we understand these stories, so when appropriate, I will fit them into context.


Despite the fact that the Kumeyaay inhabited the area for the longest amount of time, about 12,000 years before the Spanish settled, much of that history was unfortunately lost in time. What is left are fragments of such histories, changed or altered by the perspectives of later eras and usually racially charged, as the Kumeyaay were once seen as inferior to San Diego’s later inhabitants. The early story of the Kumeyaay is full of tragedy and great loss. At one point after the Mexican-American War, native men, woman, children and infants were literally hunted down and killed on site as some early American settlers attempted to completely eradicate the natives from land that used to belong to them. Before then, the native’s heritage and history had been slowly degraded by Spanish influence. It’s important to preserve what is left of it and I’m happy to be able to help out in doing so.


Because of the scanty information, the chapter on the Kumeyaay, before 1542, was also the most difficult to research. They kept no written records, and the ceremonies and stories that are recorded by a few historians are probably not the same as they were hundreds of years ago, but they definitely give one a pretty good understanding of what their life may have been like. Also, I don’t think it would be fair to simply end their story once the Spanish take over. In fact, much of the story of the mission era is the story of the Natives conversion to Christianity, and though they lost most of their land and freedom, they are sovereign today and have contributed to San Diego’s continued growth. So throughout San Diego’s history, I will follow their progression as they cope and adapt to the ever changing landscape from freedom, to religious persecution, to genocide, to developing their reservations into successful business ventures. The story of the Kumeyaay is ultimately a story of triumph through a brutal yet noble struggle for equality that has been waged since the times of the Spanish era and continues to this day in the form of legal court battles and political campaigns. The subsequent Spanish, Mexican, and American eras are in turn, very well documented, with previous historians laying down common narratives.


Every era has greatly influenced San Diego’s culture. For instance, you can’t hike through Mission Trails without seeing old paintings or carvings on rocks left over by the Kumeyaay. While visiting San Pasqual Valley, I came across ancient grinding stones, used to mix food and store water. Entire sections of the County, from Mission Trails, though Mission Gorge, down Mission Valley before passing through Mission Bay and Mission Beach, are all named after the Mission that the Spanish first erected in 1769 on a little hill, next to the valley. The Spanish also were the ones who first named the bay after one of their Saints, San Diego de Alcala. Later, the original town center, and Mission would be named after the man. That town center, now dubbed Old Town, is rich with historic Mexican culture, and many in the area still speak Spanish. It is a combination of that culture, with the power of Americanized commerce and military influence today that dominate the county, and will ensure that there are plenty of stories to tell.


With that said, in this edition, I will be so bold as to suggest an older era into the narrative. The Kumeyaay, Spanish, Mexican, and American people chose to settle and defend this coastal area for various reasons, but one reason was common among them all: San Diego was a wonderful, natural harbor, with a cool climate, and abundant natural resources, which allowed all four eras to live and thrive. The mountains to the east, Point Loma to the north, and Coronado to the west protect the bay from heavy winds and storms. The ground and rain water that flows down from the mountains in rivers provided an ample amount of fresh water to drink. How did land, that only a few million years ago, was completely submerged underwater come to have all of these attributes? In order to understand this, we need to cross disciplines into geology: The natural history of San Diego.


Understanding San Diego’s geological history was actually easier than I thought it would be. Wind, water and fault lines, acting over millions of years, slowly changed the coastal landscape into what it is today. Once the ocean levels fell and mini-fault lines raised the northern portion of the county’s coast, coastal eddies and winds blowing inland from the southwest eventually curved the bottom portion of the county into its current shape, and also gave birth to the Silver Strand and Mission Beach areas.


I will get into more detail about San Diego’s geological past in the next chapter, but I want to further justify my reasons for adding a geological era in the first place. I believe history is more than just the stories we pass down. Just as I found the story of the Kumeyaay in fragments, despite thousands of years of dominance over the land, San Diego’s geological era dominates the rest in timescales, but is also fragmented, and takes some interpretation. I’ve noticed that whatever the historical subject is, we usually tend to begin our histories without explaining much about the geological history of the land. It’s important that we understand the lay of the land before we start letting people dance on it.


My goal is simple: Tell a full account of San Diego’s history, its land and its people, from geological times to the present. I also hope to link these events to the larger context of world history, and how events in San Diego link to larger events in the world, like World War 2 and the Space Race. I am also a big fan of origin stories, so one of these chapters will tell the many backstories leading up to Cabrillo’s voyage, from ancient Chinese myths, to dead people with healing powers, to Hernán Cortés and his escapades. I hope you learn a lot, and find the stories simple to understand.


Some of these stories are mature and can be vicious at times. While I will try to keep these stories as classy as possible, I don’t want to whitewash our history, because I don’t think hiding our past from view is helpful to the reader, or anyone looking to find historical lessons. History is an opportunity to learn from the actions of others. It’s an opportunity to analyze mistakes from the distance and safety of time to see what could be done better in the future. If we are smart, we take what we learn from the past and apply those lessons to the present in order to affect the future in a positive way. It’s my hope that the reader can take away not only a few interesting tales, but maybe even a few life lessons.


I am still on the edge of the pier. The sun is now gone, though the western sky is still lit. I turn around to look at the moon again, now glowing bright as the eastern sky begins to darken. As I stare at it as if I’ve never seen it before, it feels as though I can actually see it slowly drifting over me and I think about all the other people around me watching the sunset, and the moon rise. I then think about the fact that as much as the landscape and residents of San Diego have changed in the last couple hundred years, one consistent thing is that people from all of these eras, from the first inhabitants up to me, have probably been watching sunsets from this coast for thousands of years, marveling at its beauty. The more things change, the more they stay the same. Human nature changes very rarely, and in some ways, it’s comforting. So why write a book about San Diego? I believe that humans have probably been telling each other great origin stories from the start of our species. It’s part of what it means to be human. I'm simply continuing that tradition.
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