This is a spare time work in progress and who knows when it will be done.
Recently, a picture was posted of the old Marshfield (Coos Bay) round house on a Coos Bay Rail Fan Facebook page and one question led to another and one of the questions was whether any of the track that was part of the round house complex exists today. To aid in understanding the track layout as it was in the 30's, A Southern Pacific survey of the Marshfield yard was posted and you can click here to see this survey blueprint. (This file is very large so be patient while it downloads.)
For perspective in the blueprint excerpt below:
To answer the original question, none of the actual roundhouse track exists. The two tracks that are side by side and go into the "Car House" still exist and run across Thomas and Son's parking lot in front of their office as shown in this picture. (Click on image for a larger view.) The other track to the North of these two tracks run along the North edge of Thomas and Son's parking lot and currently is the home to the infamous baggage car as well of much of it is currently covered with piles of ballast.
In the image below, the track with the red overlay between the roundhouse and the track in the parking lot was probably just about right where Thomas and Son's administrative offices are at. The roundhouse would of been where the existing warehouse is at.
In the exerpt from the original blueprint, I have overlaid in colors some of the track.