Discover and read the best of Twitter Threads about #cretaceous

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1. This History Thread is about mining of an array of minerals in Burma (Myanmar) where the geology features varied north-south belts of ores that have long been exploited and exported without protection for environment or workers.
2. Burma trade routes for gems and metals including lead and silver date back to ancient times. #Shan ruby mines were known in 6th Century. #Kachin jadeite was first significantly traded to China (where it would become the obsession of Emperors) in 1784.
3. 1886 British troops took Mogok ruby mines. British surveyed southern Burma tin deposits 1888-1912. Bawdwin, Namtu Shan St. (mined from 15th C. by Chinese) under British exported silver, lead, zinc; future US President Hoover mining engineer there. WW2 Japanese held Bawdwin.
Read 17 tweets
Interesting outcome of the DePalma et al #PNAS paper will be implications for study & interpretation of K-Pg 'Event Deposits' close to the #Chicxulub crater. These are fascinating outcrops which *could* record the same processes as 'Tanis' but have proved controversial.. (1/)
Many marine K-Pg boundary sites around the Gulf of Mexico contain evidence for high-energy deposition by processes linked to the immediate aftermath of the impact event such as earthquakes, tsunamis/seiches. But a 'catastrophist' vs. 'non-catastrophist' debate has raged.. (2/)
The 'non-catastrophist' argument has centered on biostratigraphic evidence - i.e. that diagnostic Cretaceous #fossils are found stratigraphically *above* these deposits - and suggestions they are sequence boundaries/lags/hiatuses linked simply to sea level change. (3/)
Read 16 tweets

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