This is the original cover painting by Shaw for Book #2 in  Charles Sheffield's Heritage Universe series, the sequel to "Summertide", created for the Lithuanian version of the novel published by Eridanas as "Divergencija"  in 2000 (I show the cover for reference) - and it was also seen on page 57 of Shaw's "Electric Dreams - The Art of Barclay Shaw", 1995 Paper Tiger Press.   This is clearly one of Barclay's major works, large and beautifully rendered in acrylics on board approx 42" x 30" (possibly larger)