What is that cone-shaped concrete structure in the Providence River? We found out

Katie Landeck, Providence Journal
Updated ·2 min read

At the mouth of the Providence River, there's a cone-shaped concrete structure that seems somewhat inexplicable.

The structure is near the Pomham Rocks Lighthouse.

"It has no lights and no markings, and is, at night, a bit of a navigational hazard," a What and Why RI reader wrote in to say. "What is it?"

Here's what we were able to find out about it.

The object in question, near the Pomham Rocks Lighthouse in the Providence River.
The object in question, near the Pomham Rocks Lighthouse in the Providence River.

Origin of the 'milk jug' near Pomham Rocks Lighthouse

It's known as "the milk jug," according to the director of communications and marketing at Save The Bay, Katy Dorchies Nutini.

"My captains were all over this," she wrote in an email. "The structure in question is colloquially referred to as 'the milk jug,' and it was originally constructed in 1828 to aid navigation."

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The structure, called a pyramidal daymarker, was built to mark the Pomham Rocks at a time when shipping traffic was increasing in the Providence River. According to Lighthouse Friends, the original marker had a vane and black ball on top of it.

But without the ability to help ships navigate the waters in the night, the daymarker wasn't enough. In 1870 Congress approved $20,000 to build three lights in the Providence River: Pomham Rocks, Sassafras Point and Fuller Rock. Of the three, the Pomham Rocks Lighthouse is the only one left.

Bonus question: Why are they called Pomham Rocks?

Because this is the type of question we often address in this column, here's how Pomham Rocks was named.

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"The name 'Pomham' is derived from a Narragansett Native American sachem" who was killed during King Philip’s War in 1676, according to a report on the lighthouse by Roger Williams University.

What and Why RI is a weekly feature by The Providence Journal to explore our readers' curiosity. If you have a question about Rhode Island, big or small, email it to klandeck@gannett.com. She loves a good question.

This article originally appeared on The Providence Journal: What's the cone-shaped structure near Pomham Rocks? We found out