Centers explained to us a little of the lighter or lower summer layers and the darker winter bands. His interest in these bands is not so much the principles of sedimentation as their chrono-logic significance. He there- fore is always on the lookout for the dark blue green very fine paired winter layers that he refuses to as the snowy layers. During the summer when the ice melts, the sediment is brought to the lake and the course material is soon deposited. I was surprised to see that it is this summer material that is raising bands, consisting of coarse material of various degrees and colors. It is often the grain over of seed. deposited in any year, and when the banding is thick it makes up as much as 98% of the whole seed layered down in any one year. Usually the summer layers may in thickness between 1/4 to 7/8 inch, but may get sufficient coarse sands and muds. In sedimentology most may be learned from the summer layers but for chronology dependence is had in the winter