how is the rubber mat on a conveyor joined?

Question

looking at a the conveyor belt it appears to have no joins in it but the belt runs for approx 10km supplying a power station,

Answer 1

conveyor belts, like tires are hybrid materials, not just rubber.
The rubber is coated onto a woven matrix of steel, fiberglass, canvas and or other materials. This controls stretching, and wear resistance. The mesh can sometimes be fabricated in a loop for a small radius - like a tire .

A larger radius may become a belt by welding, glueing or stitching a rubber coated matrix.

The seams may be diagonal to prevent tearing, and are often layered where seams from different layers do not overlap.

A final coating or two (inside and out) of rubber may also hide and protect the seam from snags in underliing rollers or from the items being conveyed.

Answer 2

some sort of adhesive i would quess .