An Earthquake Field Trip with Kids

This actually begins early on an April morning in 1906 when Mother Earth let loose a massive earthquake about four miles west of San Francisco. Not only did the quake lead to massive damage in that fair city but also to cities and towns like San Jose and Palo Alto, thirty to forty miles to the south. Throughout the region, massive land shifts took place leaving toppled buildings, landslides, crumpled roads and surface ruptures as evidence of that destructive force.

100 years later I find myself leading a group of school children out onto Monte Bello Ridge in search of evidence of that massive quake and the root cause of it all: the San Andreas Fault. This field excursion is a part of a program developed by volunteers under the guidance of Environmental Volunteers, an organization founded to provide hands-on science experiences to elementary school children.

So, a few days after a 90-minute classroom presentation featuring learning stations on such subjects as the rock cycle, plate tectonics, fault types, seismograph or seismic shake table, the students find themselves standing on an open ridge surrounded by little but grassland, hills and, to the west, the tree covered coastal mountain range. I assure the six to eight students in my charge that the entire two hour hike will not be spent just talking about geology and tectonics for that would be too boring. Here surrounding us is nature at its best and that we will explore holes, tracks, scat, trails, plants, ants and anything else that might present itself to us that day.

From the ridge we can see the long linear valley to the south that was created by the San Andreas. On a clear day one can see the tip of Mount Loma Prieta where, nearby, the 1989 earthquake was centered. But today that is not possible so we concentrate on the line of trees before us and note how this line bends off to the left before disappearing below the undulating hills. Now we discuss plate boundaries and how that line of trees marks the fault and that those hills on the other side belong to the North American Plate, while where we stand belongs to the Pacific Plate. It is here we discuss, despite our closeness to the fault, why we would be safe if a large quake were to strike nearby, right now (their classroom environment verses where they are standing, i.e.: there is nothing to fall on them).

I can see a few eyes beginning to glaze over and know that I have talked too long so our group moves on down the trail. “What’s this?” “Poop!” “No. Here we call it scat.” The scat is examined, looking at size and shape and, if dry, contents to determine what animal might have left it and what might have been eaten. Further on we find coyote bush, occasional wildflowers and the invasive yellow star thistle. Pressure ridges are discovered and discussed and then we come to my favorite place where each student is given a rock, which I choose. Then through the magic of a chemical reaction (HCL reacts with calcium) they discover an important clue as to where the land they are standing on came from.

We arrive at the tree-lined fault itself and find the large sag pond and the flora and fauna associated with it: newts, snails, frogs, salamanders, oaks, vines, lichen and moss are all items for exploration. Winter rains bring Bitter Boletes, Turkey Tails, Jack-o-Lanterns and Earthstars (Mushrooms/fungi), all worth a moment or two of examination. Somewhere along the way I always have two special questions to ask, “Why do plants have leaves?” and “Why do plants have flowers?” Rarely do I get easy answers and so we spend a few minutes with each, exploring the complexities of nature.

By now, we have crossed the road to the Los Trancos Preserve and the North American Plate. Here we look for the telltale slopes and terraces but they are now mostly covered by the under-story of this mixed woodland landscape. It is here we encounter an ancient looking fence, built to resemble the one that crossed the fault that April morn a hundred years ago. The rancher found a four-foot gap in his fence, a visual display of the distance the earth had shifted in this area.

Finally we cross back to the Pacific Plate side and wind our way up the trail to return to the parking lot. New plants present themselves as we enter into the Chaparral plant community so brief stops are made, not only to discuss the new species but also to catch our breath. Then it is onward and upward, hoping that the air will have cleared enough so we can see the trace of our famous fault as it heads northwestward, under the Crystal Springs and San Andreas reservoirs to exit the peninsula in Daly City.

Upon reaching the end I always hope to have time to review what has been discovered and observed. “Give me something you learned today.” Usually answers relate to animals, rarely to the purpose of the trip. ”What did you like best today?” Again the animal related items rate high, especially if we have seen a newt. Good-byes are said from both sides and we head our separate ways: I, hoping they will remember something valuable from this experience on Monte Bello, and that my efforts will not have been in vain.

February, 2007

Posted on February 8, 2011 11:14 PM by bob-dodge