The content and activities in this topic will work towards building an understanding of the physical features on the ocean floor. Scientists know more about the surface of the moon than about the bottom of the ocean. The broad size of the ocean floor, its depth and its combination of extreme conditions cold, dark, with intense water pressure all contribute to making its exploration difficult. Early civilizations believed the ocean floor to be a smooth bowl, devoid of features or life.
To preserve these articles as they originally appeared, The Times does not alter, edit or update them. Occasionally the digitization process introduces transcription errors or other problems; we are continuing to work to improve these archived versions. Oahu's lost half has been missing for some time, probably a million years or more, but only recently have the missing pieces been located. The new oceanographic surveys have mapped in greater detail the massive fields of avalanche debris. Some of the fragments are gigantic blocks measuring 10 miles on a side. New land observations also suggest that as a large part of the island plunged into the sea, a titanic ocean wave swelled up against the neighboring island of Lanai, reaching a height of 2, feet.
Thus, the southeast island is volcanically active, whereas the islands on the northwest end of the archipelago are older and typically smaller, due to longer exposure to erosion. The age of the archipelago has been estimated using potassium-argon dating methods. The Hawaiian Volcano Observatory of the USGS documents recent volcanic activity and provides images and interpretations of the volcanism. Almost all of the magma of the hotspot has the composition of basalt , and so the Hawaiian volcanoes are composed almost entirely of this igneous rock. There is very little coarser-grained gabbro and diabase.