Used my Round Ripple Formula for Flat Circles.
Abbreviations: rnd=round, dc=double crochet, ddc=decrease double crochet (two dc into one dc), ch=chain, SS=small shell (3dc into one st), LS=large shell (5dc into one st), st=stitch, Vst=V stitch (dc, ch2, dc), dbl V st: double V st (2dc, ch 2, 2dc)

Pattern: (written down after completion and not checked for accuracy)
With dark denim, into magic loop, ch 3, 11dc, from now on join to complete round and ch 3 to start next round which will count as 1dc.
Rnd 2: 24dc (2 dc into every st)
Rnd 3: 12 V st (use every other st)
Rnd 4: 12 dbl V st (into peak of V st below)
Rnd 5: SS, ddc, ddc around
Rnd 6: LS, ddc, ddc around
Rnd 7: (SS, dc, ddc, ddc, dc) around
Join washed denim color
Rnd 8: (LS, dc, ddc, ddc dc) around
Rnd 9: (SS, 2dc, ddc, ddc, 2dc) around
Rnd 10: Continue as established, alternating rows of SS and LS. The number of dcs after a LS row will increase by one on each side of “hill”. Change color every 3 rnds.

After 29 rnds, add insert being sure to sl st beginning and end of rows to the “hill’s” every other st. Find the “valley stitch” and attach washed denim and work back and forth.

Row 1: LS
Row 2: 2dc, SS, 2dc
Row 3: 3dc LS, 3dc

Attach dark denim and continue working as before, but now over 24 points. If necessary, make adjustment to stitch count to ensure all sides have same number of sts.

Color order was reversed at this point.

Since there are now 24 points, you must increase less often than every other row or work will wave. Periodically fold work in half and if it makes a semi circle and not a crescent, you are increasing at an appropriate rate to make afghan lay flat.

Work 14 more rows, finishing with a LS row to help points lay flat. May finish with reverse crochet edge if desired.