Why do historians and critics believe that modern art has ended?

art historians, art critics, curators, art institutions, and the like, recognized a distinct shift that took place, marking the end of Modernism and the beginning of the contemporary age. Modern art is that which was created sometime between the 1860s (some say the 1880s) and the late 1960s (some say only through the 1950s). Art made thereafter (e.g., conceptual, minimalist, postmodern, feminist) is considered contemporary.

Beyond the time frames, there are conceptual and aesthetic differences between the two phases. Art was called “modern” because it did not build on what came before it or rely on the teachings of the art academies. 

melody. a series of single tones which add up to a recognizable whole is called a what kind of layers of sound are heard melody or harmony. how many layers