No, he helped design the earth, but his SPECIALTY was fjords. That is what he won the award for. IIRC, he got pretty miffed when earth was destroyed, but had even grander design ideas for earth II. I think the mice kicked away his ideas though.
Indeed, I have wondered on the role of the Magratheans in the design vs construction as Deep Thought you would think designed the Earth but they were clearly tasked with much of the superficial dressing. One of those extra geeky questions one could have asked Adams when he was alive but I guess Rory McGrath who Magrathea is named after might have discussed it.
