- Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial because its bulk composition is richer in aluminium silicates (Al-Si) and has a lower density compared to the oceanic crust, called sima which is richer in magnesium silicate (Mg-Si) minerals. Changes in seismic wave velocities have shown that at a certain depth (the Conrad discontinuity), there is a reasonably sharp contrast between the more felsic upper continental crust and the lower continental crust, which is more mafic in character.
- 1985 (Wikipedia)
1985 (MCMLXXXV) was a common year starting on Tuesday of the Gregorian calendar, the 1985th year of the Common Era (CE) and Anno Domini (AD) designations, the 985th year of the 2nd millennium, the 85th year of the 20th century, and the 6th year of the 1980s decade.