Sea Cliff [above), a manned deep-submergence vehicle operated by the U.S. Navy, was used to directly ol 

 the sea bottom and to take physical samples with its mechanical arms. The Navy's unmanned Advanced 

 Tethered Vehicle (above right) was also used to take video footage and still photographs of the sea floor. 



Two types of equipment using sound waves sidescan sonar and seismic-reflection systems were 

 used to map the sea floor in the Gulf Of the Farallones. Each system is housed in a hydrodynamic 

 "towfish" that is towed just below the ocean surface from a ship. The SeaMARd A sidescan-sonar 

 system is shown here outside of its protective shell. The inset shows the towfish that was used for 

 high-resolution seismic-reflection systems. 



This U.S. Geological Survey 

 camera sled, towed from a 

 research vessel along pre- 

 planned tracklines, was 

 used to take pictures of the 

 sea floor in the Gulf of the 

 Farallones. 



Samples of the sea bottom were taken with two 

 devices. A gravity corer (above) was used where 

 the sediment was expected to be soft and muddy. 

 A clam-like Van Veen grab sampler (left, in closed 

 position), used where the sea floor was expected to 

 be sandy, collected samples such as the sand and 

 brittle stars shown (top). 



Techniques and Technology of Exploration in the Gulf of the Farallones 5 



