Usually with biotite , but also may have hornblende . . All sedimentary particles larger than two millimeters is called gravel. Gravel is subdivided into pebbles, cobbles, and boulders. Greenstones contain sodium-rich plagioclase feldspar , chlorite , and epidote , as well as quartz. The chlorite and epidote make greenstones green.
Gullies hold water for brief periods of time after a rain storm or snow melt.
The time required for one-half of the atoms of a radioactive substance to decay. . A measure of a mineral's resistance to scratching. The hardness of a mineral is measured by scratching it against another substance of known hardness. Headlands are projections of land that stick out into a sea or lake. . Holocene An epoch of the Quaternary Period beginning 10,000 years ago and continuing today. .