Dear Ian,

Thank you for contacting Mearto with your appraisal inquiry.

The presented object appears to be a watercolor drawing on paper with the measurements of 21 x 28 inches including the frame. The artwork depicts rock formations and was made and is hand-signed by the artist Bertie Stroup Marah. Sadly no further information regarding the biography of this artist is mentioned in reference books or similar databases except that he was active/lived in Colorado and is known for Figure-genre-frontier, landscape. This artwork was made in the middle or second half of the 20th century.
Works by this artist were recently not offered and sold on the international auction market.
This piece is in good condition and there is no serious damage visible in the images provided.
A fair market estimation would be between 150 to 350 USD.
This estimate is based on actual recent past recorded auction sales of comparable items. Retail "asking prices" can be higher and may vary.

With kind regards,
Georg