The weather was spectacular this Sunday, making our field trip to Crystal Crescent Beach that much more wonderful. Anne Marie Ryan and her husband Bob, both geologists, shared their knowlege of rocks, rivers, and more enthusiastically with the group. We explored river dynamics by testing the pH of several little streams as they flowed to the oceans. They each had different values – one of them was 1400 ppm. The units on the pH meter are in ppm – that means “parts per million.” That’s a hard amount to imagine! Anne Marie gaves us some ways to try to imagine it. One comparison I found online is that one ppm is like one drop of water in a 50 litre tank (like a car’s gas tank), or is like 32 seconds out of year.
We also explored stream flow rate by sending some sticks flowing down a stream and timing their voyage (18 seconds to flow 1 meter for one stream), and saw stream features like mini point bars.
As we got to a rockier part of the beach, Anne Marie challenged us to see the difference between two types of rock. The different rocks formed at different times in the beach’s past, and from them the soil was partly formed, and from that lichens and vegetation could start colonizing. Some of the rocks had scratches on them from the last retreat of the glaciers… about 10,000 years ago!
As we wandered back to our cars, some familes stayed longer to soak up some rays and play in the sand. Thank you to Anne Marie and Bob for their execellent interpretation of the geology of Crystal Crescent Beach, and to all the families who joined us on our walk.
Please take a look at the photo gallery that goes with this field trip report!