Gully Formation

Here is a a link to a picture http://hirise.lpl.arizona.edu/PSP_003583_1425 that shows gully formations on Mars. These gully formations are strong evidence that some sort of fluid flow created these gullies. As you can see from this picture, to the non-trained eye of someone like us, it looks like any real formation that could be found on earth. Is this convincing evidence there was once water on Mars? Look at the picture and see what you think