ᐅ Adhesive/Mortar for Granite Wall

Hello everyone,

I would appreciate your expertise and am already very grateful for your help.
Now to my problem:

I want to build a slope about 1.20 m (4 feet) high and about 16 m (52 feet) long. The idea is to create a wall from granite stones. I bought granite stones sized 40 x 20 x 20 cm (16 x 8 x 8 inches) and had all four sides cut because I simply liked them (typical woman).
But now everyone is making me worry that this won’t hold the slope.
However, the stones are already here and cannot be returned.

What kind of adhesive/mortar or whatever would you recommend? With as little joint as possible.
Or is it really true that the wall won’t hold?

I am really grateful for any tips!

Best regards

1.20 m (4 feet) is ambitious – hopefully without any live load behind it? With a sloped installation, proper backfilling, and a solid foundation, it probably won’t topple immediately. However, neither the manufacturer, the structural engineer, nor the contractor will likely guarantee this.

Could you possibly split the 1.20 m (4 feet) across two levels? With appropriate spacing, this would be much safer to implement.