It might be linoleum but my first guess would be rubber sheet flooring.

I think jfc is spot on with rubber sheet flooring laid out as a runner as it looks to thick to be linoleum. As far as how it is attached, that is $100,000 question. I do believe this is the same way my grandparents house was but i was too young to have cared how it was attached, lol.

Thank you! I'm going to experiment to see what I can do the get it up without ruining the wood. Will let you know what happens..

The best way is to use something wide and stiff but too sharp. Something like this:

http://www.homedepot.com/p/Razor-Back-7-in-D-Handle-Forged-Scraper-Chopper-2672200/204476157

If it is felt back it is absoutely asbestos and dont mess with it. The felt is almost 100% asbestos. Some of the mastics they used back then were asbestos also btw, even if the flooring itself isnt asbestos. I would be wary of messing with it, it reminds me of the felt back vinyl I have seen. Test the floor and if it isnt felt back then test the adhesive also. Getting the adhesive off will require sanding and you wont want to do that unknowingly to asbestos.

Thank you. I will check for felt. I am hoping to get to it this wknd!

Before sanding try throwing dry ice down on top of it to fracture the adhesive and then using a long handled floor scraper to take it up. When it works it's much faster and easier than sanding to remove most of the material and generates little to no dust.

Let us know what you find. That dark marbling pattern reminds me of old hospital and school flooring - it might be extra-thick real linoleum (often called "battleship linoleum" for its thickness), or one of the early thick commercial rubberized floors.

I would start by trying to slide a sturdy and slightly sharp blade under it to see how brittle the adhesive is. Sometimes it gets brittle enough to shatter it if you hit it at the junction between glue and wood.

One of these painter's tools will work for the early exploration:

http://www.homedepot.com/catalog/productImages/1000/c9/c964ca3c-9fcf-40f3-8606-0f356f1199fe_1000.jpg

To minimize damage, scrape with the grain of the floor as much as possible.

Asbestos is less dangerous than the scary tales you read on the net. The people most likely go get lung cancer from it are heavy smokers who are also ... asbestos miners and manufacturing personnel, professional asbestos removers, people who sprayed asbestos fireproofing with no protective gear.

1 - Don't sand it and sniff the dust. Pry and scrape chunks off, bag them and send the out with the trash.

2 - The mastic can usually be softened with steam and scraped off the floor, and there are adhesive removers that work well.

Thank you. I'd like to try it this weekend. We found out the floor guy will be coming on Friday so we have been preparing the first and second floor which has delayed us. The third floor is a totally different project (and labor of love!). I will report back .