In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil. The top of the bedrock is known as rockhead and identifying this, via excavations, drilling or geophysical methods, is an important task in most civil engineering projects. Superficial deposits (also known as drift) can be extremely thick, such that the bedrock lies hundreds of metres below the surface.

Bedrock may also experience subsurface weathering at its upper boundary, forming saprolite.

A solid geologic map of an area will usually show the distribution of differing rock types; i.e., rock that would be exposed at the surface if all soil or other superficial deposits were removed.

Erosion is the process by which soil and rock are removed from the Earth's surface by natural processes such as wind or water flow, and then transported and deposited in other locations.

While erosion is a natural process, human activities have dramatically increased (by 10-40 times) the rate at which erosion is occurring globally. Excessive erosion causes problems such as desertification, decreases in agricultural productivity due to land degradation, sedimentation of waterways, and ecological collapse due to loss of the nutrient rich upper soil layers. Water and wind erosion are now the two primary causes of land degradation; combined, they are responsible for 84% of degraded acreage, making excessive erosion one of the most significant global environmental problems we face today.

Industrial agriculture, deforestation, roads, anthropogenic climate change and urban sprawl are amongst the most significant human activities in regards to their effect on stimulating erosion. However, there are many available alternative land use practices that can curtail or limit erosion—such as terrace-building, no-till agriculture, and revegetation of denuded soils.

Louis Armstrong (August 4, 1901 – July 6, 1971), nicknamed Satchmo or Pops, was an American jazz trumpeter and singer from New Orleans, Louisiana.

Coming to prominence in the 1920s as an "inventive" cornet and trumpet player, Armstrong was a foundational influence in jazz, shifting the music's focus from collective improvisation to solo performance. With his instantly recognizable deep and distinctive gravelly voice, Armstrong was also an influential singer, demonstrating great dexterity as an improviser, bending the lyrics and melody of a song for expressive purposes. He was also greatly skilled at scat singing (vocalizing using sounds and syllables instead of actual lyrics).

Renowned for his charismatic stage presence and voice almost as much as for his trumpet-playing, Armstrong's influence extends well beyond jazz music, and by the end of his career in the 1960s, he was widely regarded as a profound influence on popular music in general. Armstrong was one of the first truly popular African-American entertainers to "cross over," whose skin-color was secondary to his music in an America that was severely racially divided. It allowed him socially acceptable access to the upper echelons of American society that were highly restricted for a black man. While he rarely publicly politicized his race, often to the dismay of fellow African-Americans, he was privately a strong supporter of the Civil Rights movement in America.^{[citation needed]}