I was looking at the lighthouse friends website at the lighthouses from Illinois. They are odd circular shapes and are referred to as cribs (ie..68th Street Crib, 4 Mile Crib, William E. Deever Crib.) Anybody know why they are cribs? Any of the above would make an interesting LE or CF lighthouse, IMHO.

Cathy

I believe these are all water intake locations for the city of Chicago.

On the floor of the lake below those locations is the actual intake pipe which then runs under the lake bed to the city's water intake plant.

When building the water systems, typically what is done is they start with a tunnel on land leading out to the under-lake location and then tunnel up to the lake bottom.

Of course, if they punch a hole in the bottom of the lake while tunnelling up, the tunnel would be flooded while it is under contruction. So they must punch through into dry land.

How? By pounding steel planking in a circular pattern around the spot where the tunnel is to come through the lake bottom. Then pumping the water our of this crib-like enclosure till the lake bottom is dry. This structure is also known as a 'coffer-dam'.

Each of the lights are on top of the covered cribs in these Illinois lights. I'd say the purpose of these lights is, of course, to warn shipping away from the structure rather than guide them into the Chicago docks or harbor.

The city of Detroit built a water intake tunnel in lower Lake Huron near Port Huron in 1971 using this system. While under contruction, an explosion happened in the tunnel under the lake and 21 were killed. I believe they ran into a pocket of methane gas while tunnelling.

Here is the story of this tunnel and the explosion from the Detroit News Archives. There is a good diagram of the construction project in the story.

There is also a crib light off of Buffalo NY.

When there is no need for a bottom intake pipe, cribs of wood were built, floated out into the water, filled with rocks and sunk. Concrete is then poured over the top to create a foundation for the lighthouse.

White Shoal MI is an example of a lighthouse built in this way.

More information on Cribs

Thanks John...as usual you are a fountain of information! I appreciate the explanation, I've never seen anything like these cribs. I learned something new today...always a good thing.

Cathy

From the CG Historian\'s page :

Thanks, John and Dave. It is always great to learn something new. I always wondered what "crib" meant as well.
Judy

Cathy,

Thanks for asking the question about "cribs." Like Judy, I always wondered what that meant. But in my case, I was reluctant to ask -- figuring the everyone knew except me.

bobo

I never knew exactly how they worked. If I saw a lighthouse and saw that its name was "crib", then I could kind of see a similarity between it and other crib lights. But I'm also crazy.

I learned something today!

Good comment Greg.

But many years ago my Dad told me that if I don't learn something new every day, I'm already six feet under. Think about it.

bobo