A usually steep slope made up of broken off pieces about 3 inches in
diameter of basalt or other lava flow created rock which cooled rapidly
enough to cause the non-crystalline formation.
This is almost impossible to ride over on a bicycle so one must hike the
bike over it.
Another funny definition is: two steps up,
one step slid down.
A four hundred foot basalt talus slope
would really be difficult to climb.