The Waterman Erratic- A really big one hidden in the woods.
By Dave Tucker February 11, 2010. Revised July 8, 2011.
This hulking brute of an erratic is 38 feet (11.6 m) high, and measures 60 feet on each side (18 m). Circumference is 155 feet (47 m). (July, 2011: This erratic is no longer the reigning “Mother of All Erratics” on this website. It has been surpassed by the Lake Stevens erratic, described here. The Waterman erratic remains a worthy geologic site to visit.) It is on a hiking trail in the Saratoga Woods Preserve, northwest of Langley, on Whidbey Island. The rock is slightly foliated greenschist, like Coupeville’s ‘Big Rock’ (see below). It could be from the Fidalgo Formation at the north end of Whidbey, or maybe the greenschist on Blanchard Mountain (see Oyster Dome geo hike). It doesn’t look like Shuksan greenschist. The monolith is vertical on three sides, and leans back only very slightly on the west. As of this writing, there is a rotting rope hanging down this face- do not get any ideas to use it! I couldn’t tell what it might be attached to on top. There is also a set of dog leashes tied together and dangling from a limb of a small tree growing along the south side- some near-disaster? The erratic is crackless, rounded, and quite smooth. It is well worth the visit. The vista at the parking area looks across inland waters of the Salish Sea, and includes the entire span from Baker south to Rainier. There is a very good view of the elusive Glacier Peak.
The challenge is on: who can find a bigger erratic west of the Cascades? Provide a photo and carefully-taken measurements.
Getting there: Find your own way to Langley, in the SE portion of Whidbey Island, on the shore of Saratoga Passage. The few E-W streets are numbered. Go to the corner of 2nd and DeBruyn, onthe west edge of town. Continue west on 2nd, which becomes Saratoga Road. Saratoga Woods Preserve is on the left 2.5 miles from the corner with DeBruyn St. There may be maps at a sign in the parking lot. Take the ‘Wood Nymph Trail ‘from the north end of the parking lot; go right on ‘Bent Tree Trail’. About 10 minutes from the car, you will cross an overgrown airstrip, now a dirt road. Waterman erratic is 200′ the other side of the airstrip, in the deep woods. A trail map published by the Whidbey-Camano Land Trust is located here (off my site).
The Coupeville Erratic
By Dave Tucker January 4, 2010.
There are many erratics studding the landscape of Whidbey Island; virtually the entire island consists of glacial deposits. I already mentioned the 10′ sandstone boulder from the Chuckanut Formation at Useless Bay. This erratic in Coupeville is a big one; some say it is the largest in the state but I’m pretty sure it is smaller than Waterman’s. The Coupeville erratic, locally known by the inspired name of ‘Big Rock’, is 30 feet tall and festooned with ivy. A smallish patch of rock is visible; I examined a spalled flake lying on the ground. The rock is very green, evidently the victim of low-grade (meaning relatively low temperature and low pressure) metamorphism so that it is now chlorite-rich. It looks very much like the rock exposed at the south end of the Deception Pass Bridge, immediately south of the restrooms on the highway. This rock, part of the Fidalgo Group, was originally a submarine volcanic breccia shed from an island volcanic chain, later accreted to North America. If that is where this rock came from, then it wasn’t hauled very far by the Vashon ice, perhaps only 14 miles.
Getting there: You can take a gander at this on your way to the Keystone ferry if you are coming from the north. Take Highway 20 to Coupeville on Whidbey Island. Turn south on South Main, at the big pedestrian overpass. The erratic is behind the coffeeshop on the right, tucked up against a house and some apartments (‘Big Rock Apartments’, of course). Park in the coffee shop parking lot, admire the boulder, then go get a cup of joe and a yummy pastry.