Last time I used my garmin striker this is pretty much what it looked like on the whole pond.  Is this a thermocline? This was set on auto gain low and if i manually adjusted the gain it would go away but it seemed like I like a lot of bottom resolution.

 

 

Thermocline shows from the bottom and up to the temperature change.  I think what you are seeing is suspended matter.

Gain is too high, and showing particulate clutter in the water.

^ lower your gain and set the bottom manually.  I see a lot of that in full auto mode

I will try turning down the gain and taking all the auto functions off.