Odd pattern printing a flat box

I get this odd pattern when printing a flat box first layers; it is a 100x100x1.2mm box.
The darker side in the picture is the first layer.
Each strip in the picture is about 2-4 mm wide (not all strips are the same width).
Infill is 0.5.

Does anyone know why do I get such an odd pattern ?

Inaki.

It might help to know what software you’re using, what settings you printed with, material, temps, that sort of thing.
Did you use a Lulzbot provided configuration for the material you printed with?

I am using Slic3r with the profiles provided by Lulzbot. Temperatures 235c and 85c.
Profile:abs medium quality non support.

Inaki.

Turn your Z axis adjustment knob down a bit, so that it decreases the initial homing height.