The Waterman Erratic- A really big one hidden in the woods.
By Dave Tucker February 11, 2010. Revised July 8, 2011.
Waterman Erratic. My camera tipped slightly, plus it is a wide angle view. DT for scale; I am 6 ft tall.
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
Big Rock. Island County Commissioner Angie Homola and her daughter Kira. Angie says she is 5 ft tall, so the erratic is about 22' (6.7 m) tall.
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.
Coupeville's Big Rock in 1963. Courtesy Donn Charnley.
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.
Northwest Geology Field Trips 
The Waterman Erratic is definately worth the effort to visit! The hike is more than 10 minutes though; it took about 40 minutes each way with pauses to look at wildflowers… and, of course, the bent trees. Very enjoyable. Once past the old airstrip, I almost killed myself going down the really steep slope to the erratic, but it was still an amazing sight. I’ve only seen one other Western WA erratic [MUCH smaller, on Camano Island]; I’m more familiar with erratics in Central WA. Thanks for the directions, there wasn’t a kiosk when we visited & we never would have found the right trail. Great website!
[…] During my morning walk I got a good picture of Coupeville’s “Big Rock”. Most people never see this rock but it’s right beside the Big Rock Apartments on South Main Street. I don’t know exactly where this Glacial Erratic Rock came from but it’s bigger than a house. You can read all about it and other erratic’s on Whidbey Island at Northwest Geology Field Trips. […]
I live right by the “big rock” and I am amazed by it. I wondered where it came from. I thought it must be from some kind of volcano or other extreme natural occurrence. Thank you for giving me more information on this rock. I have never heard of an erratic before reading this article.
Graham,
Not by fire, but by ice. Amazing, isn’t it? Glad you found my description and explanation useful.
Dave Tucker
I was wandering around Fort Casey and found an erratic in some trees by the upper parking lot and picnic area. I had just learned about erratics and was quite excited about this find. Just wondering if anyone has examined and, if so, what their conclusion are about its origins.
Megan, don’t know anything about the erratic you mention. Don’t recall noticing it. Is it very large?
Dave Tucker
We didn’t have anything to measure it with, but looking at the picture of my husband standing on top of it, I’d say it’s about 12′ H x 15′ W x 25′ L.
I wondered about the big rock at Fort Casey. I’m surprised it isn’t mentioned here except by a viewer.
Hello Caralyn, Much of what appears on this website is submitted by readers. If you want to send in a photo of the Fort Casey erratic, and directions to view it, please feel free. D. Tucker