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 theory of plate tectonics is a relatively new scientific concept. While its forerunnerâthe theory of. continental driftâhad its inception as early as the late 16th century, plate tectonics only emerged and. matured as a widely accepted theory since the 1960s (see This Dynamic Earth booklet).
Plate tectonics. Plate tectonics is a scientific theory that describes the large-scale motions of Earth's lithosphere. The model builds on the concepts of continental drift, developed during the first few decades of the 20th century.