What is It? for July 26

Directions to alien landing site....?

Recent discovered exit sign in North Africa believe to be of Neanderthal origin. Wrong blog.

So we have a winner!

Yes, indeed!

I was going to approach this tongue-in-cheek and say that it is a part of Fred Flintstone's navigation system.

Your answer seems worthy of a GA.

This:

is just 5 miles from my house.

Volunteers still maintain the rocks used to make it and paint it periodically.

About the arrow signs:

Concrete Arrows & The U.S. Airmail Beacon System

GA, I can recall seeing this on history channel a few years ago as well.

It looks like it is poured concrete. Judging by it's condition (no cracks or breaks), it had to have been place there recently, within maybe 10-20 years, possibly by the U.S. Air Force for guidance purposes. Maybe pointing toward area 51? The picture was taken around 1300 looking west.

They made good concrete 100 years ago.

Maybe so, but that piece of concrete doesn't show any signs of cracks or chipping which would be the case for a hundred year old concrete.

Concrete only chips or cracks if something chips or cracks it.

In the abscence of vehicles running over it or other impacts, all it does is weather to that lovely weathered concrete colour.

I've seen loads of old concrete that is neither cracked or chipped.

I've also seen new concrete which looks terribly abused.

I beg to differ.

As the water in the mix evaporates the resulting concrete loses internal volume. Even reinforced concrete cracks.

Period, end of story.

Then there's too much water in that mix. Concrete doesn't dry, it sets.

Yes all concrete micro cracks in tension. It doesn't crumble away though.

The post I responded to was a claim that all 10 to 20 YO concrete is cracked and chipped. Even unloaded slabs as pictured.

Maybe if the microcracks get water in them and then freezes and thaws repetitively it might prematurely destroy the concrete.

Colon, story continues.

Yes, concrete "sets", as in there is a chemical reaction that hardens the concrete.

The water is there to facilitate that reaction, and then it goes away.

It does not become part of the concrete.

Too much water may cause the concrete to set improperly and crack, yes.

In spite of the fact we have a winner, I say it is for hopscotch for the giants mentioned in the Bible.

An arrowhead, of course. You find them all over wherever Native Americans lived. They didn't have flint that size, so they made them out of concrete. They planted sequoias to make the arrows and redwoods to make the bows.

For bowstrings, they used a thousand feet of braided shoreline.

The only question is, what were they hunting?

Islands and continents!

is it the way to Armorilo?

It's an arrow, it points North, and the picture was taken between 1 and 2 in the afternoon.

Direction pointer for aeroplanes. Before boyscouts

It's interesting to think about:

1. How they determined where to put them

2. How they found the sites from the ground

3. How they got the concrete, tents, food, forming materials and water to the site

4. How they mixed and poured the concrete

5. How long each arrow took to finish.

In 1957, my father worked for the USFS one summer in Sequoia NP, building bridges. Mules and hand tools were all the crews had. They rode to a site, cut native trees and built bridges over canyons and creeks.

Same thought. No helicopters.

That's the key to Superman's other fortress, the Fortress of Dehydration.

Very nice.
For the unitiated:
http://comiccoverage.typepad.com/.shared/image.html?/photos/uncategorized/2008/03/24/s_176_2.jpg