Fossilized wood/bark from Pennsylvanian strata?

[tombk]

Today after work, I went to a new-to-me site in Iowa City. I had seen an old online pamphlet walking tour of the geology of the University campus. They listed a site they described as Pennsylvanian sandstone/siltstone in which they said there may be impressions of wood fossils. Here’s a piece I found:

 

 

It’s very fragile, so I’ve only done some very light cleaning with a soft brush. Here’s a closer image:

 

 

Here’s an even closer image where you can really see the grain. 
 

 

Am I right in seeing wood here?

Edited July 2, 2021 by tombk
Arranging the images

[Lone Hunter]

Kinda looking like sandstone to me, but pictures of the ends would help.

[tombk]

Here’s a picture of the side as requested by @Lone Hunter  The side looks like typical sandstone, no organization beyond clumped-together grains. This makes me wonder what was responsible for creating the larger-scale patterns of longitudinal striation on the flat of the rock. (See pics in original post.)  Any thoughts? Thanks. 
 

[JohnJ]

Research slickensides.

[tombk]

I did look up slickensides. That answers my question! I’m disappointed I didn’t find a fossil, but I learned something new. Thanks @JohnJ!

[Mark Kmiecik]

Fossil wood is almost everyone's first reaction to slickensides, including me.