Iron formations in the Lake Superior region are about 2.2 billion years old, dating from the Early Proterozoic Era. In Geology of the Lake Superior Region, Gene LaBarge writes that similar iron formations occurred in other places around the world about the same time, but that there were no iron formations after the end of the Early Proterozoic, about 2.0 billion years ago. This raised an interesting question for geologists, What happened that would cause deposits of iron mineral on a massive scale to occur and then never reoccur?
Some geologists believe it was the advent of our oxygenated atmosphere that led to the iron formations and that has prevented formations since. Prior to the Early Proterozoic Era, iron was dissolved in the seas and oceans. At that time the earth’s water and atmosphere were deficient of oxygen. Iron is soluble in oxygen deficient water; it is not, however, soluble in oxygenated water.
With the evolution of photo synthetic organisms and their explosive growth during the Early Proterozoic Era, oxygen gradually became plentiful in the air, and in the water. As oxygen levels increased, iron began to precipitate out of the water and settle in huge quantities on the floor of seas and oceans. Since water became oxygen rich, no more iron has dissolved in the water, hence, no large iron formations have reoccurred.
Grenville had probably been considering a Stamp Act in the Country colonies since 1763. Best places to travel in winter in USA He proposed it to the House of Commons on March 9, 1764, primarily so that Parliament could affirm its ability to tax the colonies. He stipulated, however, that the colonies had a year in which to propose an alternate source of revenue. This offer to the colonies of finding a means to tax themselves was immediately suspect, as colonial agents could not get Grenville to give them any solid procedure by which they could offer such plans or have them approved. Meanwhile, the Earl of Halifax, as secretary of state for the South, surveyed the colonial governors via a circular letter, inquiring about the many documents that might need to carry a stamp. Although the colonists protested through their agents, including Benjamin Franklin, there was little organized resistance by the time the measure came to the House of Commons in February 1765. Drafted by Thomas Waltey of the Treasury, the schedule of stamp duties covered all printed material and legal documents, including playing cards, newspapers, diplomas, and ship clearances. The fees were generally far lower than those that residents of England already paid, with the exception of the fees for matriculation certificates and professional bona fides, with the purpose of discouraging lower-class Countrys from gaining them.
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