Sitting midway on Rockingstone Avenue is a huge boulder after which the street is named.

It was so perfectly balanced that it could be gently pushed with one hand, from an easterly direction, and would rock to and fro before settling, never falling over. It is thought that its bottom tip balanced perfectly on a great boulder base.

In one iconic photo, circa 1913, a man poses atop it.

The boulder--eleven feet high, sixteen feet long, thirteen feet across, and weighing 150 tons—is a "glacial erratic" (meaning a boulder transported by Ice Age glaciers), and no longer rocks.

It resides in the part of Larchmont that is in the Unincorporated Area of the Town of Mamaroneck.

Traffic runs on either side of the stone, and three streets merge into it: Poplar Road; and Spruce Road, renamed Springdale Road on the opposite side, heading into New Rochelle. Rockingstone Avenue would be the natural continuation of North Chatsworth Avenue if the latter did not veer to the right after leaving Larchmont Village. 

Gloria Poccia Pritts, Village of Mamaroneck Historian, was born in 1924, and remembers that there were many glacial erratic boulders in Mamaroneck when she was growing up.

"This is the last remaining one that I know of," she says.

Today, the boulder is obscured by shrubs, trees, and signs, and dwarfed by large houses.

Recently, Yolanda Garagatti, of Hartsdale, rounded the stone.  A nursing aid, she drives around it daily to visit a patient.  "I use it to give driving directions. One day I gave instructions to my sister, telling her to go around the trees. Later my sister told me, 'It's a big stone,' and so I took a closer look. I've wondered about it."

The rocking stopped

The boulder once sat in a wooded location.

The area was surveyed by William Bryson for the Chatsworth Subdivision Map.  Bryson, a New Rochelle engineer and surveyor, carved his name and the date of completion, 1853, into the rock. To find the carving today, face the side with the yellow diamond sign, and pull back shrubbery from the lower left of the boulder.

The Daily Times reported in March, 1963, that  "…many residents remember rocking the stone. It was quite a sport in the first quarter of the century, as was chestnutting in the woods around it, recalls Mrs. Mabel Wood Smith who moved to Larchmont in 1906."

In her book in Mamaroneck Town: A History of the "Gathering Place," Paula B. Lippsett, M.D., surmised that the stone stopped rocking in the 1920s due to dynamiting in the area to build sewers and regrade the land, and when Rockingstone Avenue was resurfaced with concrete.

That work destroyed what The Daily Times aptly described as "the delicate balance of the rocking mechanism, and the great stone settled into its present immovable position."

Communication and landmark legend

The boulder made an audible "whoosh, whoosh" sound when rocked.  In her research, Pritts learned that "some sources claim that Native Americans used it as a kind of message sender. I don't know if it's true."

Legend is that the stone would be rocked in a form of audible code, "because you could hear the sound from its movement through the woods."

Because of the immovability of the massive stone, it was often used for demarcation.

* Siwanoy used it as a tribal territory marker when lined up with a stone in Yonkers and another at Throg's Neck. 

* The boulder was a landmark on Hannah's Peak which is the highest point near the Sound in Westchester County, wrote Lippsett.

* It was the western marker for the eight lots that John Richbell laid out after purchasing land from Wappaque-wam in 1661. 

* Additionally, it marked the northernmost holdings of Samuel Palmer who bought the middle section of Richbell's purchase in 1701.

In Colonial times, it was called Rattlesnake Hill and Chestnut Hill.

The Daily Times reported that at one time, the stone "marked the old town boundary between Mamaroneck and New Rochelle, though the line is now slightly to the west of the stone."

Changing times

Glacial erratic boulders were removed with area development.

Pritts recalls being a student at Central Elementary School, now where Mamaroneck Town Hall is located. "I was probably eleven years old. I remember there were two groups of erratic stones, not as high as 'rocking stone,' but still very tall. We used to climb all over them at recess and play 'King of the Rock.'" 

Two parking lots have replaced those boulder locations.

Still, there is an abundance of rock ledges in our area.

"But a rounded rock the size of 'rocking stone'? That's the work of rolling inside the glacier," says Pritts,  "and we have one."

Katherine Ann Samon is the author of four books, including Ranch House Style, and is a Larchmont Historical Society trustee. Her column, "Historical Wonders," about important buildings, people, and events  in Larchmont and Mamaroneck, appears twice a month on Larchmont-Mamaroneck Patch. To learn more about the author, visit her Web site: www.katherineannsamon.com