The cuttings (chips of ice cut away by the drill) must be drawn up the hole and disposed of or they will reduce the cutting efficiency of the drill.
The fluid must have a low kinematic viscosity to reduce tripping time (the time taken to pull the drilling equipment out of the hole and return it to the bottom of the hole).
- Sexy brazilian chat
- colorado dating on line
- Chatham kent girls nude pic
- signs of an online dating player
- Completly free local sex chat
The bubbles disappear and the ice becomes more transparent.
The weight above makes deeper layers of ice thin and flow outwards.
The proportions of different oxygen and hydrogen isotopes provide information about ancient temperatures, and the air trapped in tiny bubbles can be analysed to determine the level of atmospheric gases such as carbon dioxide.
Since heat flow in a large ice sheet is very slow, the borehole temperature is another indicator of temperature in the past.
In Greenland, a sequence of collaborative projects began in the 1970s with the Greenland Ice Sheet Project; there have been multiple follow-up projects, with the most recent, the East Greenland Ice-Core Project, expected to complete a deep core in east Greenland in 2020.