第一段:Grand Canyon 拥有最完整和研究序列的岩石。时间从2 billion years 到200 million years。 包含marine + terrestrial sediments.
第二段: GC 形成的猜想(it is believed )
Uplift of region -> exposure of rock -> Rocky Mountains
同时:邻近的Basin + Range Province formed crustal stretching
导致-> drainage system flowed to eastern GC -> lower Basin + Range province.
Seismic activity -> gulf of California -> larger river cut gulf -> form Colorado River -> form GC
第三段: climate (ice age) 加速GC excavation -> river volume decreased -> volcanic activity -> lava blocked Colorado River -> slowed canyon -> fin of ice age + human activity reduced CR to deepen the canyon.
所以形成了现在的大峡谷。
(No change until major shifts in river volume)
At least 13 lava dams blocked the Colorado River over that time period, forming lakes that were up to 2,000 feet (610 m) deep and slowing excavation of the canyon. 这句话太鸡贼了,竟然把减慢excavation放在最后,直接没看到啊啊啊啊