Concrete Footer Part 3 Video
Here is the concrete that has hardened up overnight. But notice the groove in the center of the footer? The groove is called a keyway. What the keyway does is forms a way to mechanically interlock the foundation walls, that sit on top of the footer, to the footer. This makes it harder for the foundation walls to shift sideways off the footer when the weight of the backfill soil is placed against the foundation.
If you recall, the footer had to go up over some solid bedrock. Here you can see the form for making the vertical step in the footer to get to the higher elevation. You can see how they made the forms to contain the concrete at the step. At the other end of the footer rise, there is another step form. You can see some concrete that oozed out the side where they didn't put in a form board. This would have saved some concrete, but it is not the end of the world.
This is what a concrete foundation footer looks like the day after pouring. The contractor will come back today or the next day and strip off the footer forms. They will then start setting the panels for the foundation walls. And I will be back to show you that step.