XP Deus /Teknetics T2 Classic/Garrett Pro Pointer II
Regarding the (paraphrased) question of what happened to the old rails the answer is, it depends. Around my area there were many logging railroads at the turn of the century. When the economy changed in the 30's they were simply ripped up for scrap. I was able to ID two lines within 3 miles of my home using a 1919 topo map and some software/phone app (Maprika). It led me straight to them. What remains are the old dirt roadbeds which are now used as dirt roads into the respective properties (several hundred acres of pine forests).
On the other hand there is a CSX mainline several miles in the opposite direction from my home. I had researched the route that southern forces had taken when Charleston was evacuated. Those units that couldn't fit on the last trains out were forced to march, following the mainline of one of the major railroads in the area during the 1800's. I narrowed down a good search area to detect and went on my very first researched hunt. Lo and behold I located the remains of the original roadbed and ironically it paralleled the CSX mainline..the present day owner of that original railroad. CSX eventually acquired it through various mergers of southern railroads through the years. From the RR related artifacts I found while detecting it appeared the original roadbed was utilized until sometime in the 30's. When the line was upgraded it appears they simply laid a new mainline adjacent to the original and once completed they ripped up the old one and abandoned the original roadbed. Operationally this would make sense as they could still operate the mainline on the old tracks until the new section was done and then switch over with very little interruption in operations.
To say I found a few old rail spikes would be an understatement! My first find was a fired enfield round (which was posted last year). After that it was a ton of spikes!! Being in newbie learning mode it was a "dig everything" hunt. That lasted until about my 15th spike! LOL
ive seen that on some of my maps as well but there's no key saying what it means so I'm not sure either
There's a RR museum either in or close to Las Vegas might want to give them a call or send an email with a screen grab of your map showing the X mark. They were a big help to my buddy when he was looking for info on the Calif area.