The admission of California would upset the balance of power in senate between the Southern slave states and the Northern Free states
Basically, it was bringing gain (money) to the people who profited from it.
Slaves were cheaper than other labour and needed on the plantations: they brought profit to their masters and this profit could be "invested" into buying more slaves.
Navigation of the American Explorers - 15th to 17th Centuries
Seventeenth century travelers to Maine’s coast such as Samuel Champlain, George Waymouth, and John Smith carried state-of-the-art navigation tools for both dead reckoning and celestial navigation.
Navigation Tools for Dead Reckoning and Piloting
Invented in China in the 3rd century BC, the compass did not come to Europe until the 12th century AD. By the time of Columbus' voyage it was common. Instead of degrees, the compass card, on which directions were drawn or printed, showed the points of the compass, including north, south, east, and west. There are 32 points of the compass, the four main quadrants of the circle each divided into eight 11¼ ° points. Columbus noticed that, as one sailed across the Atlantic Ocean, the variation between magnetic north and true north changed. On future trips he used this to predict, roughly, his arrival in America.
A divergent plate boundary is where two tectonic plates move apart from each other
