Emma Dean is a small impact crater in Meridiani Planum

Meridiani Planum

Meridiani Planum is a plain located 2 degrees south of Mars' equator , in the westernmost portion of Terra Meridiani. It hosts a rare occurrence of gray crystalline hematite...

 on Mars

Mars

Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

 that was visited by the Opportunity rover

Opportunity rover

Opportunity, MER-B , is a robotic rover on the planet Mars, active since 2004. It is the remaining rover in NASA's ongoing Mars Exploration Rover Mission...

 from sols

Timekeeping on Mars

Various schemes have been used or proposed to keep track of time and date on the planet Mars independently of Earth time and calendars.Mars has an axial tilt and a rotation period similar to those of Earth. Thus it experiences seasons of spring, summer, autumn and winter much like Earth, and its...

 929 to 943. The much larger crater Victoria

Victoria (crater)

Victoria is an impact crater on Mars located at 2.05°S, 5.50°W in Meridiani Planum, visited by the Mars Exploration Rover Opportunity. It is roughly 730 metres wide, nearly eight times the size of the crater Endurance, visited by Opportunity from sols 951 to 1630...

 lies about 100m to the east.
Emma Dean lies directly on top of the ejecta blanket from Victoria and could therefore expose material originating from deep inside Victoria.
The crater is named after the Emma Dean, one of the boats in John Wesley Powell

John Wesley Powell

John Wesley Powell was a U.S. soldier, geologist, explorer of the American West, and director of major scientific and cultural institutions...

's Grand Canyon

Grand Canyon

The Grand Canyon is a steep-sided canyon carved by the Colorado River in the United States in the state of Arizona. It is largely contained within the Grand Canyon National Park, the 15th national park in the United States...

 expedition.

Other craters visited by Opportunity

• Eagle
  Eagle (crater)
  Eagle is a 22-metre impact crater located on Mars on Meridiani Planum. The Opportunity rover came to rest inside Eagle crater when it landed in 2004...
  
  
• Fram
  Fram (crater)
  Fram is an impact crater in Meridiani Planum, on Mars. It was visited by the rover Opportunity on Sol 84, April 24, 2004.Fram spans about 8 metres in diameter. Opportunity paused beside it while travelling from the rover's landing site toward a larger crater, Endurance...
  
  
• Endurance
  Endurance (crater)
  Endurance is an impact crater on Mars that was visited by the Opportunity rover from May until December 2004. Mission scientists named the crater after the ship Endurance that sailed to the Antarctic in an exploration voyage organized by Ernest Shackleton.The rover entered the crater interior on...
  
  
• Argo
  Argo (crater)
  Argo is a crater located in the Meridiani Planum, on Mars, that was visited by the Opportunity rover approximately on its 365th Martian sol. The crater is located approximately south of the heat shield and Heat Shield Rock.-External links:*...
  
  
• Vostok
  Vostok (crater)
  Vostok is a crater on Mars that was reached by the rover Opportunity on sol 399 . Vostok is located roughly 1200 meters south of Endurance in Meridiani Planum...
  
  
• Erebus
  Erebus (crater)
  Erebus is a crater on Mars visited by the Opportunity rover on the way to the much larger crater Victoria. It is named after the polar exploration vessel HMS Erebus...
  
  
• Beagle
  Beagle (crater)
  This article is about the crater on Mars. For other uses, see Beagle .Beagle is a crater on Mars in Meridiani Planum which was explored by the Opportunity rover. It was located by the rover in images taken on sol 855 , 310 metres away...
  
  
• Victoria
  Victoria (crater)
  Victoria is an impact crater on Mars located at 2.05°S, 5.50°W in Meridiani Planum, visited by the Mars Exploration Rover Opportunity. It is roughly 730 metres wide, nearly eight times the size of the crater Endurance, visited by Opportunity from sols 951 to 1630...