Need help to bend terrain into a "horse shoe" shaped object.

[Haroldsworld]

Hello and thank you for helping me out here (Jan in Oslo, Norway)

I am asked to 3D modeling of a deep ocean trench.
This particular trench is shaped like this: First a several mile long straight sub sea trench with mountains on the side, above water, then the trench bends into a half circle and continues in a straight line for another several miles. Like a horse shoe shape, but not that narrow. My problem is, how do I make the bending of the trench into a half circle. In other words I have never cut out a semi circle from a rectangle. I attach two picture of a straight line-type sub sea trench that I have made. They are from another trench job I did last month, but they will give you some idea of what I do. Thanks a million times from Oslo!

[mhaze]

Use a painted shader attached to a displacement shader with negative displacement.  or a simple shape shader bent with a redirect and a powerfractal.  The former is easier to control the shape.

[mhaze]

here u go

[Haroldsworld]

Hello,
Yes, I found it. As you see, I am new to this. The pictures with text have all been through Combustion. You can see the difference in the picture marked "Y" rendered in Tg, and after it has been in the Combustion, marked "13.3.2014C" I gladly do that for you whenever you need that. Get back to me if I can be of help. Thank you.

[Haroldsworld]

Hello, I send you two more pictures, after treatment in Combustion.