Two large erratics have been excavated in a new housing development in Ferndale, Washington. They were found during construction at Malloy Village, which is north of Ferndale High School. The developers, Michael and Katharine, moved them to the new neighborhood park. While looking on the internet for information on erratics, Katharine found the Donovan erratic story on this blog, and now here they are, on the blog, too! Serendipity reigns supreme.
These are both great examples of Jackass Mountain Formation conglomerate, similar to the Donovan Avenue erratic in Bellingham. This formation is found in the area around Hope, B.C. and Manning Park. One of these boulders is quite round, and is 7 1/2 feet high. The larger is 9 feet high, and is a little more angular; it has some nice glacial polish and subtle striae on the west face. Numerous rounded rock fragments, or clasts, can be seen in the boulders. Most are either granitic or volcanic, but there is quite a variety- see how many different rock types you can identify. Both erratics were found near each other, mostly buried, less than 200 yards south of their current position; Michael used a bulldozer to roll them to their new places. It took 6 hours to move the more angular one; the roundish one was easier. There are a number of much smaller erratics in the field south of the new houses.
Katharine and Michael hope that these big boulders will be visited by Ferndale school groups on field trips. The plan is to make a plaque explaining the boulders, and the complex history of plate tectonics that brought the Jackass Mountain conglomerate from a far-off island arc to North America during subduction and terrrane accretion.
Getting there: NW Geology blog readers are particularly invited to come visit these cool glacial erratics. Use I-5 exit 262 (Ferndale) and go west less than a mile into downtown. Turn right on either 2nd, 3rd, or 4th and then turn left in one block on Vista Drive. You will shortly arrive at a roundabout near the High School- veer right on Malloy. In 1.1 miles, turn right on Calico Loop into the Malloy Village subdivision. I guarantee you will not miss the erratics on the right, before the end of the cul-de-sac. If you see Katharine or Michael, say hello and “Thanks”!