From pattern notes:

“This is a rectangular shawl knit in garter stitch (knit every row) from one long side to the other long side. The cast-on and cast-off edges should be very loose so that the shawl drapes well. Consider using a needle two sizes larger for both (or a different technique). The original yarn used was a 50/50 wool/mohair blend with 19 WPI, 800 YPP (yards per pound.).

The stitch pattern is based on “Seafoam Pattern” on page 218 in Barbara Walker’s A Second Treasury of Knitting Patterns (1998, Schoolhouse Press). This revision results in a reversible shawl. The pattern repeat is 10+6 stitches, so the shawl can be made about 4 1/3 inches longer or shorter by adding or subtracting 10 stitches.“