Underpinning Houston's land surface are unconsolidated clays, clay shales, and poorly cemented sands up to several miles deep. The region's geology developed from river deposits formed from the erosion of the Rocky Mountains. These sediments consist of a series of sands and clays deposited on decaying organic marine matter, that over time, transformed into oil and natural gas. Beneath the layers of sediment is a water-deposited layer of halite, a rock salt. The porous layers were compressed over time and forced upward. As it pushed upward, the salt dragged surrounding sediments into salt dome formations, often trapping oil and gas that seeped from the surrounding porous sands. The thick, rich, sometimes black, surface soil is suitable for rice farming in suburban outskirts where the city continues to grow. COUNT 10
QSN1 What materials are underpinning the land surface of Houston? ANS1 unconsolidated clays, clay shales, and poorly cemented sands QSN2 Houston's geology was formed from river deposits from the erosion of what mountains? ANS2 Rocky Mountains QSN3 The sand and clay deposited onto decaying marine matter transformed into what? ANS3 oil and natural gas QSN4 What is halite? ANS4 a rock salt QSN5 What type of farming is Houston's surface soil good for? ANS5 rice farming QSN6 Besides sands, what are the foundations of Houston's land? ANS6 clays QSN7 How deep are the clay and sands foundations of Houston? ANS7 several miles QSN8 What geological event caused the foundations of the land beneath Houston? ANS8 erosion of the Rocky Mountains QSN9 What agricultural crop was farmed in the rich soils on the outlying areas of Houston? ANS9 rice QSN10 What did the decaying organics under the clay and sand deposits later form? ANS10 oil and natural gas