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--- videos:geopolitics [2024/10/20 07:36] – [Business] jhagstrand
+++ videos:geopolitics [2025/07/09 00:26] (current) – [Map Projections] jhagstrand
@@ Line 41: / Line 41: @@
 royalty to republic (returned to the public from the ruling class)
+  * American revolution
   * French revolution
   * Russian revolution
@@ Line 46: / Line 47: @@
   * Gandhi's revolution in India
+FDR - govt over business
 Rock, paper, scissors
@@ Line 143: / Line 145: @@
 observer at the center
-horizon, a plane 5 km in diameter tangential to the observer
+  * horizon, a plane 5 km in diameter tangential to the observer
-zenith - directly over the observer's head
+  * zenith - directly over the observer's head
-celestial meridian - the circle describing the plane containing the observer, the zenith, and North
+  * celestial meridian - the circle describing the plane containing the observer, the zenith, and North
+Projections chronological
+  * Orthographic
+  * Equirectangular
+  * 1100 Azimuthal Equidistant
+  * 1569 Mercator
+  * 1772 Lambert Azimuthal equal-area
+  * 1805 Albers equal-area conic
+  * 1885 Gall-Peters
+  * 1889 Aitoff
+  * 1898 Van der Grinten
+  * 1963 Robinson
+  * 1921 Winkel Tripel
+  * 1923 Goode Homolosine
+  * 1954 Fuller Dymaxian Polyhedron
+  * 1996 Waterman Butterfly
+projection sequence
+  * Equirectangular
+  * Mercator
+  * Aitoff
+  * Fuller
+wall chart - the whole globe on one page
+  * centered on Prime Meridian
+  * centered on Anti Meridian
+  * centered on a pole
+  * add an orthographic with 4 hemispheres
+===== geosketch cheatsheet =====
+see https://docs.google.com/spreadsheets/d/1tGFLZGoImvcf8dj5HsG48Xsm_phn2BYVDNbd-ksg_W8/edit?usp=sharing
+equator \\
+null island \\
+Lake Victoria \\
+Ecuador \\
+Galapagos \\
+===== books, movies, pop culture references to geography ======
+Borat - Kazakhstan \\
+Khabib - Dagestan \\
+Captain Phillips - Somalia \\
+Somerset Maughm - Switzerland to Vladivostok \\
+Mark Greaney: Sentinel - Ghana \\
+Barbara Kingsolver: The Poisonwood Bible - DR Congo \\
+Joseph Conrad: Heart of Darkness - DR Congo \\
+Don Winslow: The Power of the Dog - South Africa \\
+Jack Carr: True Believer - Rhodesia \\
+Stephen Leather: Baltic Black Ops - Lithuania, Kaliningrad \\
+Khaled Hosseini: The Kite Runner - Afghanistan
+movie The Man Who Would be King - Afghanistan \\
+James Clavell: Shogun - Japan \\
+M.M. Kaye: The Far Pavillions - India \\
+Mark Greaney: Agent in Place - Syria \\
+Louis L'Amore: Last of the Breed - eastern Siberia \\
+At 33:43 in, Indiana Jones picks up Marion in Nepal and then takes a plane ride over a map to Cairo \\
+At 1:38:04 in, our heroes are traveling west in the Mediterranean from Cairo to London, but end up on a u-boat that travels back east through a map between Greece and Crete to an island in the Agean Sea \\
+====== Drake Passage ======
+John Hagstrand <john@hagstrand.com>
+Wed 18 Jun, 14:00 (1 day ago)
+to me
+The formation of the Drake Passage, the body of water separating South America (specifically the southern tip of Patagonia) and Antarctica (the Antarctic Peninsula), is a fascinating chapter in Earth's geological history. It occurred roughly 41 million years ago during the Eocene epoch, driven by tectonic plate movements and associated geological processes. Below is a detailed explanation of how it formed, the tectonic context, and its significance.
+### Tectonic Context
+The Drake Passage's formation is tied to the breakup of the supercontinent **Gondwana**, which began around 180 million years ago. Gondwana included what are now South America, Africa, Antarctica, Australia, and India. By the Cretaceous period (about 100 million years ago), South America and Antarctica were still connected, forming part of the remnants of Gondwana. A narrow land bridge or series of volcanic arcs, often referred to as the **Andean-Antarctic Isthmus**, linked the two continents.
+The key tectonic players in the formation of the Drake Passage were:
+- **South American Plate**: Moving westward due to seafloor spreading at the Mid-Atlantic Ridge.
+- **Antarctic Plate**: Relatively stationary but influenced by surrounding plate dynamics.
+- **Scotia Plate**: A smaller plate that later emerged and played a role in shaping the region.
+- **Nazca Plate and Phoenix Plate**: Oceanic plates subducting beneath South America and influencing regional tectonics.
+The relative motion of these plates, combined with global tectonic reorganization, set the stage for the opening of the Drake Passage.
+### Formation Process
+The opening of the Drake Passage was a gradual process, spanning millions of years, driven by **continental drift** and **seafloor spreading**. Here’s a step-by-step breakdown:
+. **Initial Separation (~50–41 million years ago)**:
+   - Around 50 million years ago, South America and Antarctica began to drift apart due to tectonic forces. This was part of the broader separation of Gondwana, where South America moved northward and westward, while Antarctica moved southward toward its current polar position.
+   - The **West Antarctic Rift System**, a region of crustal thinning, facilitated the stretching and subsidence of the crust between the two continents. This created shallow marine basins, allowing seawater to encroach into the region.
+. **Development of a Proto-Drake Passage (~41 million years ago)**:
+   - By approximately 41 million years ago, tectonic extension and seafloor spreading had progressed enough to create a deep-water channel between South America and Antarctica. This marked the initial opening of the Drake Passage.
+   - The **Scotia Plate** began to form as a result of complex interactions between the South American, Antarctic, and oceanic plates. Seafloor spreading in the Scotia Sea further widened the gap.
+   - The exact timing is debated, with some studies suggesting a deep-water connection as early as 50 million years ago, but most evidence (from ocean sediment cores and paleoceanographic data) points to a significant deep-water channel by 41 million years ago.
+. **West-to-East Ocean Flow**:
+   - The opening of the Drake Passage allowed for the establishment of the **Antarctic Circumpolar Current (ACC)**, a powerful west-to-east ocean current that encircles Antarctica. This current was a game-changer for global climate and ocean circulation.
+   - Before the passage opened, the land bridge between South America and Antarctica restricted ocean flow, keeping Antarctica warmer. Once the ACC formed, it isolated Antarctica thermally, preventing warm ocean currents from reaching the continent and contributing to its glaciation.
+. **Geological Evidence**:
+   - **Ocean Drilling Program (ODP)** cores from the Southern Ocean show changes in sediment composition and microfossils around 41 million years ago, indicating the onset of deep-water circulation.
+   - **Magnetic anomalies** in the Scotia Sea reveal patterns of seafloor spreading, confirming the tectonic widening of the region.
+   - **Paleomagnetic data** from South America and Antarctica show their relative drift over time.
+### Timing and Debate
+While 41 million years ago is a commonly cited date for the opening of a deep-water Drake Passage, the precise timing is still debated. Some studies suggest:
+- A shallow marine connection may have existed as early as 50 million years ago.
+- Full deep-water circulation, enabling the ACC, likely solidified between 41 and 34 million years ago.
+- The **Eocene-Oligocene boundary** (~34 million years ago) marks a significant global cooling event, often linked to the full establishment of the ACC and Antarctic glaciation, suggesting the Drake Passage was fully open by then.
+### Significance of the Drake Passage
+The formation of the Drake Passage had profound effects on Earth’s systems:
+- **Climate Change**: The ACC isolated Antarctica, leading to its widespread glaciation by cutting off warm ocean currents. This contributed to the transition from a "greenhouse" to an "icehouse" Earth during the Eocene-Oligocene transition.
+- **Ocean Circulation**: The ACC connected the Atlantic, Pacific, and Indian Oceans, reshaping global ocean currents and influencing heat distribution.
+- **Biodiversity**: The isolation of Antarctica led to unique evolutionary paths for marine and terrestrial species, while the ACC created a barrier for some marine organisms but a dispersal pathway for others.
+- **Geological Evolution**: The Scotia Plate and surrounding tectonic features continued to evolve, shaping the modern Southern Ocean and its islands.
+### Modern Drake Passage
+Today, the Drake Passage is one of the world’s most treacherous waterways, about 800 km (500 miles) wide at its narrowest point. It’s notorious for stormy seas and strong currents, driven by the unimpeded flow of the ACC and westerly winds. The passage remains a critical chokepoint for global ocean circulation and a focal point for studying Earth’s climatic and tectonic history.
+### Supporting Data
+- **Geochronology**: Radiometric dating of volcanic rocks in the Scotia Sea and paleomagnetic studies confirm the timing of seafloor spreading.
+- **Paleoceanography**: Oxygen isotope records from deep-sea sediments show a cooling trend around 41–34 million years ago, tied to the ACC’s onset.
+- **Tectonic Models**: Reconstructions using plate motion data (e.g., from GPS and magnetic anomalies) illustrate the drift of South America and Antarctica.
+If you’d like, I can dive deeper into specific aspects, like the paleoceanographic evidence, the role of the Scotia Plate, or the climatic impacts of the ACC. Alternatively, I could generate a visual representation of the tectonic movements or the ACC’s path—let me know if you want me to confirm for image generation!