By Cynthia Robertson
SDSU professor pens book on the geology of Mission Trails Regional Park
When Dr. Patrick L. Abbott hikes in Mission Trails Regional Park, he is reading between the lines — of the rocks, that is. A Professor Emeritus of Geology at SDSU, Abbott’s passion for the language of rocks compelled him to write a book about this favorite park of his.
Mission Trails Regional Park Foundation has just published and released Dr. Abbott’s newest book: “Geology — Mission Trails Park.”
Focusing on the past 126 million years, Dr. Abbott has divided history of the park into four stages:
126 to 90 million years ago, magma is injected above and below ground-building mountains.
90 to 57 million years ago, erosion carves a new and lower landscape.
57 to 34 million years ago, the park is literally buried by a massive alluvial fan built of gravels delivered by a 225-mile-long river.
34 million years ago to now, erosion is exposing parts of the once-buried landscape as well as eroding new topography.
With master’s and doctorate degrees in geology, Dr. Abbott is well-equipped to understand the history in rocks.
“My specialization is reading the history in sedimentary rocks,” said Dr. Abbott, who was born and grew up in San Diego and graduated from Hoover High School.
For his Ph.D. dissertation, he wrote about the geologic history of the Edwards Limestone Aquifer, which supplies the water needs of the city of San Antonio. Existing within the Balcones fault zone, the aquifer has a 100-million-year history involving stops, starts and pauses, Abbott explained.
Dr. Abbott had first become interested in geology in courses taught by Baylor Brooks at San Diego State College.
“I adopted geology as my major at the start of my junior year. The appeal of geology is that it combines the best of both arts and sciences. You need artistic creativity first, but then you can apply the rigor of the sciences to see how close to the truth you can get,” he said.
Dr. Abbott wanted to pass along the new data and esoteric understanding of the park to as many people as possible.
“I call it legacy writing,” he said.
The book is not his first on geology. He wrote another excellent tome on San Diego geography, “The Rise and Fall of San Diego.” He also wrote “The Balcones Escarpment,” a popular book about a Texas geologic formation formed along the fault of the same name running from the southwest to the northeast portions of Texas.
Here in San Diego, Mission Trails Regional Park is a wealth of geologic formation and writing in the rocks of history.
“We are truly fortunate to have a huge wilderness park within the city limits of one of the largest cities in the United States,” Dr. Abbott said.
But until now, the geologic history of the park had not been studied together as a whole. Dr. Abbott’s book has made that knowledge available, and signage within the park will come soon.
“It’s not so much that Mission Trails Park contains things that are different, but that it has good examples that can be readily accessed and enjoyed in a park that must remain wilderness for future generations,” he said.
It was a pleasant journey for Dr. Abbott to write “Geology – Mission Trails Park.”
“I wrote it while working on other projects. Since much of the data and geologic understanding in the book are brand new, the writing was interspersed with many hiking trips to ‘look and learn,’” he said.
The “look and learn” hikes are detailed within the book.
Some examples are taking the 5-Peak Challenge, climbing each peak. The rocks are former magmas that crystallized about 1.5 miles deep, sometime between 118 to 104 million years ago.
“The views are great, and your health will improve,” quipped Dr. Abbott.
At the Visitor Center Loop Trail, you can see a fault exposed in a cutback of the San Diego River. On the south side of the fault are 126-million-year-old volcanic rocks; on the north side are 113-million-year-old plutonic rocks.
On the other end of the park from Clairemont Mesa Drive, walk through whitish-color Eocene sedimentary rocks about 42 million years old.
“They contain the whitish mineral precipitate caliche which tells us about the climate of its time,” said Dr. Abbott.
Simply walking or driving through Mission Gorge, “our own little Yosemite Valley,” Dr. Abbott said, you can see the San Diego River cutting down through high mountains. Want to know how?
“It’s in the book,” Dr. Abbott said.
Geologic curiosities surround Lake Murray, as well, in its Eocene-age conglomerate.
“Look at the reddish-purplish cobbles and boulders of volcanic rock brought from mainland Mexico by a huge river. How did the river get across the Gulf of California?
“The answer is in the book,” he said.
The book is good for all ages, written for the general public. “It presents real geologic knowledge. It probably should be thought of as an accessible textbook—put some effort into reading it and you will learn new things,” he said.
Dr. Abbott would like to thank David Cooksy for his many photographs in the book. Steve Boudreau, Monte Marshall and Abbott also have some of their photographs in the book. Clever drawings and cartoons by geologist Jake Washburn as well as computer illustrations and art by geologist Eugenia Sangines make the book even more readable.
Dr. Abbott has served on the board of directors for the Mission Trails Regional Park Foundation and currently serves as an advisor. His anticipated book is available exclusively at the Visitor Center gift shop with proceeds benefitting the Mission Trails Regional Park Foundation.
— Cynthia Roberts is a San Diego-based freelance writer. Reach her at [email protected].
