Fishfinder Screen- What am I seeing? Looks weird in 450 FOW

[garrymny]

I fished in the deepest water I ever fished today, 450 feet or so. Difficult because my Lowrance elite 4X Chirp acted quite different in the deeper water. I had to change the setting to "Deep Water" setting. I saw a dark band of something down about 90-100 feet. It actually looked like it was the bottom, it was so thick, actually extending all the way to bottom.  Was this a thermocline? Any ideas? I know I should have taken a picture, sorry. There was also a fuzzy thin line at 20-30'. Definitely not my DR balls, they were down at 65 and 80-90. Just allot of different looking stuff on the screen today. Very few fish I might add.

[bottom-feeder]

possible the sesitivity was too high.... if you were near oswego last i heard temp was deeper than that

[Iceman]

It was 48 to 50 degrees down 150' yesterday from 200' fow to 600' fow.

[garrymny]

hmm, so maybe it was a temp change at that depth.