Expedition Menu

1. Welcome
2. The Idea
3. Boarding
4. Ship Tour
5. Back Deck
6. Preparing to Depart
7. Leaving
8. Meeting
9. Bay-Delta-Estuary
10. Navigating
11. The Survey
12. First Data
13. The Mosaic
14. Visualizing
15. Hazards
16. Disposal Site
17. Sediment Map
18. Compare19. Future Studies
20. Final Meeting

Contact
Don Reed
Dept. of Geology
San José State
University

We have located three of the large, shallow rocks that pose a hazard to ships on the relief map to the northwest of Alcatraz (Harding Rock, Shag Rock and Arch Rock). Let's address our first objective of the survey -- to determine the water depth to the top of each rock in order to better understand the hazard that they pose to large vessels entering the San Francisco bay.

Shaded relief maps provide valuable information on the shape of the bay floor, but we need to know about the specific water depths at the top of each one of these objects, which can be best determined from contour maps.

Determine the water depths at the top of the three rocks by clicking on the top of each (one at a time). The small numbers at the top of each rock on the map in the pop up will give the water depth in meters (3.3 feet=1 meter).