Short answers, pulled from the story.
One cubic meter of gravel weighs approximately 1,600 kilograms. This density belies the loose and scattered appearance of the material. The weight is consistent across standard measurements for this geological classification.
The Udden-Wentworth scale divides granular gravel into particles ranging from 2 millimeters to 64 millimeters. This scale is widely adopted by geologists in the United States to define granular gravel. Pebble gravel extends from 64 millimeters to 256 millimeters under the same system.
Quartz is the most common mineral found in gravel because it is hard and chemically inert. It lacks cleavage planes along which rock easily splits during transport. This durability allows quartz to survive the rounding process in rivers.
Some 960 million tons of construction sand and gravel were produced in the United States in 2020. This figure vastly exceeds the 68 million tons of industrial sand and gravel used for specialized purposes. The total value of sand and gravel production reached approximately 12.6 billion dollars that year.
Bank gravel is naturally deposited gravel intermixed with sand or clay found in and next to rivers and streams. Bench gravel refers to a bed of gravel located on the side of a valley above the present stream bottom. Bench gravel indicates the former location of the stream bed when it was at a higher level.
Plant life is generally more sparse in locales where gravelly soil is predominant. This scarcity is due to the inferior ability of gravels to retain moisture. The corresponding paucity of mineral nutrients further limits vegetation growth in these environments.