Hydraulic fracturing, also known as fracking, involves drilling down and creating tiny explosions to crack the hard shale rocks to release the gas inside.

BBC: Drilling for gas

Hydraulic fracturing or "fracking" is a process of forcing water mixed with chemicals through deep wells to shatter and crack hard shale rocks to release the gas inside.

BBC: Hydraulic fracturing

That leaves Turkey trapped between rocks and hard places, belonging fully to neither.

FORBES: Turkey, Between Rocks and Hard Places

The committee is caught between assorted rocks and hard places most weeks, now.

BBC: MPs' demand for backbench debating time exceeds supply

Bioerosion: process by which animals, through drilling, grazing and burrowing, erode hard substances, for example rocks and coral reefs.

UNESCO: L O S S A R Y

Both of the new-new notebooks also offer up to 4GB of DDR2 RAM and nVidia graphics cards, but the 9510 rocks the GeForce Go 7900 GS with 512MB of RAM and up to 240GB of hard drive space, while the 9110 has to settle for the GeForce Go 7600 with 256MB of RAM and a HDD that maxes out at 120GB.

ENGADGET: Acer Aspire 9510 and 9110 HD-DVD-sporting laptops

It's hard to know how long ago liquid water would have been there because there's no mechanism to date the rocks that rovers find on Mars, Squyres said.

CNN: Rover Curiosity near Mars landing