Table of contents

“Corona” Course at Black Diamond Mines

Black Diamond Mines Regional Preserve

Dates: July 3, 2020 to ??
Location: Antioch, CA
Course Setter:
Type: Training; Tough middle-distance course using small orange cones as control markers

Photo gallery image (click to enlarge)

February 21, 2021 Update

Control markers were removed Sunday, February 21st — a new course is available.

General Notes

I set a tough middle-distance course at Black Diamond Mines Regional Preserve (


The Junior World Orienteering Championships (JWOC ( were postponed this year. As a substitute, the athletes on the U.S. Junior National Team (including BAOC’s Julia Doubson) were challenged to complete the full series of events (Sprint, Long, Relay, Middle classification, and Middle final) over a one-week period. Several BAOC club members prepared courses for Julia. This course was designed to simulate the Middle final.


Coordinates for the park entrance are 37.9712023,-121.8627757. The Course Setter’s Notes ( provide directions from there.


The “standard” sign-in/sign-out spreadsheet is here ( Please use it.

That sheet contains a link to a webpage ( that lists the map, control description, and Course Setter’s Notes. (When you get to the webpage that lists the files, double click on an item to open it. Then you can use the download icon at the top right corner of the window to download the file to your computer.)

The course details are: 2.9 km, 240 m climb, 12 controls. As described in the Course Setter’s Notes, small orange cones are used as control markers.

The map scale is 1:10,000 with 5-meter contours. You’ll see that the course goes very close to the edge of the mapped terrain​—​be careful!

Enjoy 😊

François Léonard
(July 3, 2020)