boundaries between tectonic plates is the type of land where you find most volcanoes above sea level.
boundaries between tectonic plates is the type of land where you find most volcanoes above sea level.
in what type of land do you find most volcanoes above sea level?
boundaries between tectonic plates
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sea level rose even higher in this massive transgressive event, which helped form the 300–500 ft thick austin chalk, around ≈89-85mya. the austin formation consists of recrystalized, fossiliferous, interbedded chalks and marls. exposures of austin chalk are mainly seen in quarries, roadcuts, and stream beds where the water eroded the top soil. austin chalk is the well known white rock that the city of dallas sits on. volcanic ashes are present in the austin chalk, and were deposited by wind from distant erupting volcanoes and erupting igneous intrusions around 86 ma. these eruptions occurred along a 250 mile long by 50 mile wide belt of submarine volcanoes, which are located in present-day south-central texas. this belt of volcanoes coincides with the trend of the balcones fault zone and is known as the balcones volcanic province. of what consisted of these ancient volcanoes is only visible in a few places since most were buried by the austin and taylor groups, and now are in the subsurface. the presence of this volcanism during deposition of the austin chalk is correlated with the laramide orogeny. sea level rose for conditions to be right for the deposition of the austin chalk, which also coincides with the maximum extent of the cretaceous interior seaway. the depths of the deposition of the austin chalk occurred in ≈250m or 820 ft of water. the austin chalk formation is filled with micro-organisms known as coccoliths, and are a product of the warm waters that were displaced from the increased sea-floor spreading at the time.
geology of the dallas–fort worth metroplex