The load is largely transmitted to the floor through the beams on the sides and center of the pallets.
Ummm ... look at the picture.
Its quite clear the side beams are floating in space on every stack and are not directly supported (they are cantilevered out by the bottom planks, which appear to be 1x8's). The gold is stacked on the top plate of wood of each pallet up to the side beams, but not over them.
The gold is a simple distributed load, but more of the load will be acting on the center support than the ends.
g = the load of gold per foot
M = force on the middle beam
E = force on the outside beam
x = length of gold stack
b = width of beam beyond the edge of gold stack
Solving the normal equations of force and Moment at M:
gx = M + 2*E
E*(x+b) = (g*x/2)*(x/4)
Gives:
M = g*x + (g*x^2)/[4*(x+b)]
E = (g*x^2)/[8*(x+b)]
If x = 2.5 ft, b = 0.25 ft, and g = 900 lb/ft. (2250 lb/2.5 ft.), then:
M = 1739 lb and E = 256 lb
The load from the middle beam is going to be imposed directly down the middle of the stack, with slight distribution to the sides of the middle on each of the stacks below, while the load on the edge beams will act as a point load on the edge of the gold stack and should cause bending and a rotational deflection in the end of the 1x8 plank that lifts it slightly off the stack below, due to a lack of direct support under the end beam.
Most of the load is going straight down the middle to the floor, and should end up imposing a roughly 50 psi pressure on the floor in the 2/3 sq. ft. of the two planks on the bottom pallet that is centered on either end of the middle beam.
The only real question is whether there is a type of wood that can support the roughly 10,500 lbs load in shear being imposed on it in the bottom pallet. I suspect there is, since these loads are near to the type of loads imposed on railway ties - 40,000 lbs on an 8"x14" section of wood. This is 10,500 lbs on a 3"x8".
All they had to do was build their custom pallets with 5 riser webs.
I was thinking that the base looked like 50k# on two 2"x40" boards --coming out to about 300 psi. No big deal for the base. For the pallet boards we got for each inch of width about 200 # distributed over a 3 ft. span --believable.
I say the picture can be for real.