Physical Geography — Policy Changes

Entry	Year	Description	Impact
Theory of Continental Drift to Plate Tectonics	Early 20th Century to Mid-20th Century	Alfred Wegener's Continental Drift hypothesis (early 1900s) proposed that continents moved, but lacked a convincing mechanism. The 'amendment' or evolution came with the development of Seafloor Spreading theory (1960s) by Harry Hess and Robert Dietz, which provided the mechanism of new crust generation and movement. This led to the comprehensive Plate Tectonics theory, unifying these ideas and explaining Earth's dynamic processes.	Revolutionized geology, providing a unifying theory for earthquakes, volcanoes, mountain building, and the distribution of continents and oceans. It shifted geological understanding from static to dynamic Earth processes, fundamentally changing how we perceive our planet.
Uniformitarianism vs. Catastrophism	Late 18th Century to Present	Early geological thought was dominated by Catastrophism, suggesting Earth's features formed by sudden, short-lived, violent events. James Hutton (late 18th century) introduced Uniformitarianism, stating 'the present is the key to the past,' meaning geological processes operating today have operated similarly throughout Earth's history. While Uniformitarianism became dominant, modern geology acknowledges that catastrophic events (e.g., asteroid impacts, supervolcanoes) have also played significant roles, leading to a nuanced view.	Provided a scientific basis for understanding geological processes over vast timescales. It allowed for the interpretation of ancient rock formations based on observable modern processes, but also opened the door for recognizing the impact of rare, high-magnitude events in Earth's history.
Evolution of Climate Classification Systems	Late 19th Century to Present	Early climate classifications were often descriptive. The most significant 'amendment' came with Wladimir Köppen's system (early 20th century), which used quantitative, empirical data (temperature and precipitation) to define climate zones, directly linking them to vegetation. Subsequent refinements and alternative systems (e.g., Thornthwaite's, Trewartha's) have added complexity, incorporating factors like evapotranspiration and genetic causes, but Köppen remains foundational.	Provided a standardized, objective framework for global climate comparison and study. It facilitated understanding of vegetation distribution and laid the groundwork for climate modeling and the study of climate change, allowing for systematic analysis of regional and global climate patterns.

Also build Paper II skills

Regional comparisons and process chains train the same coherence and inference habits CSAT passages demand. CSAT hub.

• Data interpretation
• Estimation techniques
• Logical deductions