If a significant amount of water was released or mobilized by the formation of the Hale Crater impact, larger impacts that formed during the early days of the Solar System may have been able to bring even more water to the surface of Mars. If this is true, a long-term, stable, warm and wet climate may not be required to explain the presence of such channels in the ancient Martian landscapes.

It was Giovanni Schiaparelli who is responsible for the idea of "canals" on Mars. He wrote about canali in his observations; it's the Italian word for "channels", which was mistranslated. I'm glad to see the term is back where it belongs.