1 They could be symptoms of cancer of the lung, head, and neck. 2  Anyone with a cough that lasts more than a month or with blood in the mucus that is coughed up should see a doctor. 3  A change in bowel habits. 4  Most changes in bowel habits are related to your diet and fluid intake.
The theoretical model builds on the concept of continental drift developed during the first few decades of the 20th century. The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s and early 1960s. The lithosphere, which is the rigid outermost shell of a planet (the crust and upper mantle), is broken up into tectonic plates.
From the deepest ocean trench to the tallest mountain, plate tectonics explains the features and movement of Earth's surface in the present and the past. Plate tectonics is the theory that Earth's outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core.The plates act like a hard and rigid shell compared to Earth's mantle. This strong outer layer is called the lithosphere.Developed from the 1950s through the 1970s, plate tectonics is the modern version of continental drift, a theory first proposed by scientist Alfred Wegener in 1912.Wegener didn't have an explanation for how continents could move around the planet, but researchers do now.eveloped from the 1950s through the 1970s, plate tectonics is the modern version of continental drift, a theory first proposed by scientist Alfred Wegener in 1912. Wegener didn't have an explanation for how continents could move around the planet, but researchers do now.