how do i distinguish bottom types on my Lowrance x-65

[eyecatcher_1]

I have a lowrance x-65 and I am having a difficult time telling if i am on a rock bottom, sand bottom, or mud bottom. I can tell easily when using flashers, but does anyone know where there are some screen shots or examples of what the graph will look like on different bottom types? Thanks

[Cangl]

Your actual knowledge of the body of water your on for one, also rocks and stones seldom have any kind of "spatter" (loose pixels) under them or through the "hump". As a bottom gets harder, clay, shale, etc.. the black width of the first band showing narrows whereby a softer bottom will show up as a wider black line and in many cases with a real soft bottom show at what depth in the marl or what not a firm bottom starts below the stuff. Bottom bouncers and heavy jigs read bottom better then any electronics and they catch fish so when in doubt do as the "roamings" do check it out with a rod.
Excuse the pun, it could be the coffee. ;)

As far as screens I know of none other then the ones stored noggin wise with regards to the body of water. Those sunken christmas trees always look good simulated and in real life.