Did I get your attention? It sure did me when I saw this on a trail map of Cougar Mountain Regional Park. It was time to go for a hike and check it out.
But first I did some research and learned what an Erratic is. No it is not someone driving on I-5 who speeds by us weaving in and out of traffic. It is a “Big Ass” Rock. It and 14 other of these glacial phenomena have their own Wikipedia article. Link to Biggest Erratics of King County. Who could have known.
So what is an Erratic? According to Wiki they are:
A glacial erratic is glacially deposited rock differing from the size and type of rock native to the area in which it rests. “Erratics” take their name from the Latin word errare (to wander), and are carried by glacial ice, often over distances of hundreds of kilometres. Erratics can range in size from pebbles to large boulders
Wikipedia article
Off I went in late July. It was still pretty warm but with lots of water and a sandwich I set off to investigate this wonder of nature. I parked at the Anti-Aircraft Peak lot and hiked down the side of the mountain to my destination rock.
The trail started out fairly flat with some pretty foliage and even a Rock Dove who flushed up into a tree as I passed by.
A large patch of devil’s club. Don’t grab these bushes or you will be sorry 
Close up of the big leaves around spiny stalks. Another name for this plant is the Devil’s Walking Stick. 
Been so dry the vine maple is turning early 
Curtain of leaves 
Nature at it’s best in the forest 
A Rock Dove (aka Pigeon) cautiously watches me walk by.
Another little bonus along the way was a mini boulder just off the trail. Don’t be fooled by my calling it mini. It was about the size of the bed of a pickup truck.
This part of the trail was nice and easy. It sloped slightly downhill but nothing too tough to traverse. However, at about the half way mark it started to change. It got steeper and normally that would be no problem. It has been dry for so long the trail had lots of slippery things on it. It was a mix of fine gravel, roots and worst of all the dirt was a powdery and slippery dust. Thank goodness for a trekking pole but even then one had to purposely put each foot down.
At last I had my destination in sight. From a distance one isn’t even sure it is the Fantastic Erratic.
There is no doubt when one gets there that this is it. It has it’s own sign declaring that you have arrived to see something marvelous.
Are you ready to see what the all hype is about? Let us start with walking past the sign which is at the top. Around it we go to the bottom where you will see it in all it’s glory.
This is the top of the boulder – see the sign off on the left? 
The trail circles around the flank. See how the vegetation is dying from the dry weather? 
Are you beginning to see how big this baby is? 
Hard to get the scale in a photo. Just think about how it is 15 feet tall. 
See my trekking pole? Does that give you some perspective of this huge rock
This erratic is the size of a double car garage. Does that help you get a feel for it’s size? Still photography does not really capture this baby’s wonder. So… I took a video and narrated my approach to the bottom. This will help you get a feel for it’s colossalness.
I hiked back up to the sign and got myself on top. One cannot help climb a big ass rock. It is just a genetic thing we humans want to do. The Wedgewood Rock which is in the middle of that Seattle neighborhood is even bigger. At it’s tallest spot it is 26 feet vs this rock at 15 feet. So many had climbed it that the city in 1970 made it illegal to do so in an effort to protect us from ourselves. Here is a photo of it in case you have a hankering to go find it.
I digress… I walked about the Fantastic Erratic and carefully climbed on top of it. Since this boulder is on a hillside the top is pretty easy to get to. Here is a few photos of what I saw from up there.
On top of the world eating my lunch. See how close the trail is to the top and sign? 
Looking at the dusty trail that circles this erratic 
Looking down at the trail as it goes past this big rock. Don’t be fooled it is a long way down! 
Lastly, looking over the edge where it is 15 feet to the bottom. You can see the trail headed down to Hwy 900.
Hope you enjoyed this adventure and learned something new. Who would have thought Fantastic Erratic was a “Big Ass Rock”!!!!
Crows of Arroyos 
Wedgwood Rock is still doing well, beloved by neighbors and secure in its position on a parking strip. https://wedgwoodinseattlehistory.com/2012/03/12/wedgwood-rock-from-homestead-to-houses/
Ahhh..so well loved and in the middle of a city. I recently remember one I found in a Renton Neighborhood up hill from Valley General Hospital. It is not nearly as big as Wedgwood. Maybe half or a third of Fantastic Erratic.
Need to research that more.