One of the important compositional tools available to the photographer is considering the orientation and final aspect ratio of the image. One option is the classic square format. The following images are all square compositions cropped from the 2:3 aspect ration of 35mm digital captures, and each of them illustrates the strength of a square composition. The next time you are out photographing and searching for an image try thinking square!
Stephen Weaver Photography/Earth Systems Imaging : The Art of the Landscape 
Excellent post and images, Stephen. I agree and it’s also one reason I enjoy Instagram – a different creative format along with my regular shooting.