Riding On Loose Ground - Mountain Bike Zen
Loosepack or gravel, its slips.
Loose dirt and gravel can be very challenging and a lot of fun. The problem is getting traction as the loose bits act almost like a lubricant between your tyres and the hard ground below meaning your wheels can skid out from under you quickly and without warning. If you do a lot of riding on gravel or loose ground it is worth investing in some tyres that have design strengths in this area.
Skidding is much more likely on gravel or loose pack ground than it is on hard pack or vegetation. This means initially keeping an eye on your speed is very important, as soon as you apply heavy braking you will begin to skid.
As you gain more experience you will be able to use this to your advantage and it is devilish fun, but picking lots of tiny sharp stones out of your arm isn't. Unless you are on a steep decline you will want to use a lot more front brake than rear, stayed as balanced as possible and be slightly raised from your seat to enable quick reaction and weight shifting should you enter a skid.