Unlike gullies, streams rarely dry up.
That is true; these gullies have been seen by Mars landers.
by woods and swamps
, too, assume you're talking about Mars simply because of the abundance of other Mars questions on here this morning. If you're not, my apologies. Anyway, the conclusion (gullies were created by water bubbling up to the planet's surface) is based on computer modeling of the atmosphere and how water would behave. However, there are other scientists that disagree and think the gullies could have been made by dust or wind. As evidence they point out similiar gullies on the Moon, where no water has been found.
A river system
The plural of gully is gullies. As in "this is the gullies".
Water erosion trenches, created naturally by water run off are known as gullies.
Unlike gullies, streams rarely dry up.
Streams are different from gullies because it doesn't dry up.
channel erosion occurs when the gullies are too wide
A gully is a landform created by running water that has eroded the soil. Gullies resemble large ditches or small valleys.
Blackmans Gully
That is true; these gullies have been seen by Mars landers.
Gullies are formed by running water. The water washes down to low point, and the flow slowly erodes the dirt into a gully.
by woods and swamps
Both have to do with water
A network of gullies, streams, and rivers in an area