Question

A geologist is working in an area with exposed sedimentary rocks and finds a well exposed sequence of stratified rocks. As he works through a thick sequence of limestone, he sees abundant large clam fossils that produce an interlocking texture suggesting a reef, but within the limestone section these clams disappear and the overlying limestone is made up primarily of fragments of corals. He now moves 50 km away and finds limestones interbedded with shales, and the limestones contain the same clam fossils he had seen previously 50 km away. As he continues through this section, the rocks become entirely limestone, and the clams disappear again with coral fossils above forming a reef structure. He concludes ________.

Answer 1

Answer:

Corals reef is a underwater ecosystem that builds on limestone beds, CaCo3

Explanation:

• They have exoskeletons made up of limestones and its possible that the corals might have moved offshore with changes in the sea levels as, he finds an abundance of large clam fossils, that produce within the interlocking of limestone section.

• Since the clam is made up primarily of coral fragments its possible that the corals might have buried under the landmass when the upliftment was completed.  

• The skeletal remains of the coral polyps that are now stratified in the rocks are suggestive of reef formation around the landmass earlier period and these were mostly found in tropical oceans.  

• Thus as he moves away and sees limestones with shales, which has clam fossils he had seen previously.