I know of upright fossil trunks and some scientific explanations for them, but...

The swedish creationist Anders Gärdeborn claims upright fossil trunks have been found, that spans sedimentary strata being deposited over 100,000 years.

I'm trying to debunk his claims, but this was hard for me.

Do anyone know of fossils like these, and what could be a scientific explanation for that? I've never seen someone explaining fossils spanning such a "long period of time".

TalkOrigins is your friend (as with pretty much any of the Cretinist claims): http://www.talkorigins.org/faqs/polystrate/trees.html

I used Talk Origins as I usually do. Thank you!