White sediments on Chek Jawa - where is it coming from?

Today, at Chek Jawa off the boardwalk, there was a long stretch of white sediments on the high shore.

Opposite this stretch of white sediments, there was work on part of the boadwalk. Is this where the sediments came from?

A closer look at the white sediments.

Opposite the white sediments, work was going on at the boardwalk.

There were several large white large bags in the work site. I didn't have a closer look.

Otherwise, I had a great day out guiding with the Naked Hermit Crabs for our monthly free tour of the boardwalk. Due to COVID-19, we only took a small group of visitors, so each guide only took one family group or a small group of visitors.