Glacio-fluvial

In the lab manual it says that glacial till can be a mixture from fine clay to coarse fragments, but glacio-fluvial has no silt or clay. Why can't fine material carried by the glacier also be reworked by meltwater? Also, how are the fragments deposited by glacio-fluvial?

Yehuda, if glacial till is reworked by water the fines (silt and clay) will be "washed" downstream. Because glaciers carry so much material, there is not enough energy in the water to move all the material. Thus glacio-fluvial deposits are sub-rounded, and coarse.