See subject.
The ship appears to be sitting on a large steel cradle. Probably has wheels to provide a slow steady glide into the water. If the wheels are powered, the piles could be sand used for traction. Steel wheels on steel rails slip quite easily.
A wild ass guess.
Another wild guess: some of it was used to level out the metal track that the ship would slide down.
However, I don’t think of loose dirt as a great way of leveling things, so don’t put much stock in this idea.
Those little piles of dirt are waist high to the men in the picture. Each is next to a horizontal groove parallel to the two railings. I suspect that they removed those grooves to allow water to flow into the underside of the boat when they opened up the dry dock so that the boat would raise up and float out. The only reason they are not covered with water now is that the boat left the dry dock and the water receded back into the bay.
It’s a strange sort of “drydock” that has its bottom above the level of the adjacent water, and a set of ways down which a ship slides to be launched.
A normal dry dock has its bottom well below the adjacent water. A ship is docked by floating it into the flooded dock, closing gates, setting blocks that will hold it upright, then pumping out the water. To launch (or relaunch) the ship, the dock is flooded, the ship floats, the gates are opened and the ship sails away.
That’s what I thought too, strange way to design a dry dock; but its the only way I could see that the scenario in the picture made any sense. I suspect that the whole ship wasn’t in the dry dock but that doesn’t make much sense either.
Really? Where? It looks like the ones on the left are about knee high, except for the guy kneeling.
I’m more curious about the rubble between the two launching rails.
Outside the rails, it looks like properly laid pavers (or whatever you want to call them) creating an attractive and functional surface.
Between the rails looks like an old brick road (that you see in streets built in the first half of the 1900’s) that hasn’t been maintained in decades.
On a related note, quibbling about whether it’s a drydock, a launching ramp or whatever is not helpful to anybody, and actually gets in the way of a meaningful response.
I’m not sure that guy is kneeling. The others are too far away from the piles. Either way I believe it’s safe to say that those piles came from those grooves and that those grooves are their for some practical reason.
Also, I also noticed that the bricks in the middle seem broken up. Perhaps the ship actually sat on those and crushed them to a point to where it was stable. Just a theory mind you; as is all of my statements so far. Go ahead and punch holes in my theories; I’d like to know what’s going on here too.
WAG:
Swept up piles of sand blasting media.
WAG: The dry dock you linked to is at a facility that repairs ships that have already been launched. But the dry dock in the OP’s photo is at the shipyard where the ship was built. (Which is why the balloons and streamers are there; this is the launch ceremony.)
OP here. Still interested like you. Do I know what a dry dock is? 
Ship stopped==dock, no water==dry.
Although I’m glad to know now.
Also (please don’t laugh) are we looking at the back of the ship, and that bulbous projection houses the propeller works?
I think you’re seeing the bow (i.e., front end) of the ship.
Or a sleath prop!
So here’s more info than anyone wants. It’s the launch of the USNS Washington Chambers at NASSCO in San Diego harbor. The tip-off for me was those goddamned ugly high-rises out by Coronado across the bay, just visible to the right of the ship in the photo. I hate them and they’re unmistakable.
She’s an AKE (dry stores and ammo supply ship) that accompanies Marine amphib groups or carrier battle groups when on deployment. Those groups just don’t go anywhere without the grocery store and the gas station going with them.
As to the OP I just don’t know what those piles of dirt are, but now I want to find out. The objects between the slips, though, I believe are not bricks but timber shoring to support the ship under construction. They’re bigger than they appear if you check their size against the surounding people.
I have to see now about getting invited to launch: they’re doing night launches sometimes!
ETA: The bulb at the base of the bows reduces drag by lessening the height of the bow wave (a major source of drag) and has been popular in ships since around the 80s sometime.
nvm
The objects are timber blocks to support the keel during building. They can be seen stacked behind the prop here, and the stacks are torn down before launch. A higher resolution view of launching is here.
I believe the dirt piles are a result of sweeping the dock and slips before launch, but I’m not positive.
Neat stuff.
The piles still lurk unanswered…
Seems kind of undignified to slide in ass-backwards. (Always thought that about SCUBA divers too.)
Are all big ships launched that way?
Carriers certainly aren’t. They’re laid down in dry docks and then floated out. Newport News Shipbuilding, IIRC, is the only facility in the US capable of building carriers anymore.