Dunnigan is a small populated place located near the I-5 & I-505 intersection at N 38º 53’ 7” W 121º 58’ 7”. The cache is located in Dunnigan near the Community Park. There is a nice playground for the kids nearby.
The Dunnigan Quadrangle boundaries are:
N 38º 52’ 30” and N 39º 00’ 00”
W 121º 52’ 30” and W 122º 00’ 00”
The upper left-hand corner of this quadrangle is a Degree Confluence point.
The United States Geological Survey (USGS) has many missions. At one time, a major mission of the USGS was the supplying of topographic maps of the United States on several scales. Our cache series is based on the 7.5-minute quadrangle series.
The term quadrangle is used, instead of quadrilateral or rectangle, because the sides of these blocks are curved. The USGS divided the United States into quadrangles that are 7.5 minutes by 7.5 minutes. Since a degree is divided into 60 minutes, a quadrangle one degree by one degree contains 64 of these quadrangles. The USGS also produced a 15-minute series, but that’s another story.