How do you tell the age of a quilt?

I posted over in Antiques and it was suggested I ask someone who quilts.

I have some quilts that my greatgrandmother made in the early 1900's; however, I found this one with no note as to age. It doesn't fully cover a double bed. In this picture the far (not showing) edge doesn't go down like a normal bedspread would. Also, does anyone know the name of this pattern?