The relative age or the geologic period of the "bedrock" around Riverhead, NY is late Triassic and early Jurassic.
<u>Explanation:</u>
According to studies, the geologic period of the formation of the bedrock around Riverhead, NY has been reckoned to be around late Triassic and early Jurassic.
From the conclusions derived through geologic dating of the rock samples from this area, it is clear that the bedrock around Riverhead, NY is one of the oldest formed bedrocks in the United States.
