securing stones for waterfalls

Securing Stones for Waterfalls

My question has to do with an existing waterfall. I want to build the structure higher in the back so that I can add more topsoil to create a sloping effect (back to front). The waterfall is made from moss stone and I wanted to add 1 or 2 more layers around the entire back. Do I need to use any adhesive to the additional stones or can they just be place onto the existing ones and then filled with soil? If I need to use adhesive what are the best products that are available?

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Probably nothing is needed except to pile some more moss rocks and add a liner so the water won’t escape. If the rocks do seem unstable, add some cement or mortar to make the structure secure. Then, get some grout color from a flooring or marble supply house and add a final layer of colored grout over the exposed cement. Match the color of the stones and it will make the cement binding disappear. Your stone structure will appear unified and organic.