Geology

[equalsmcsquared.livejournal.com]

I hope everyone had a good Thanksgiving. If not, well, I'm sorry. *She smiles pleasantly.* There is leftover pumpkin pie and coffee near the back. Please sign the roll sheet and tell any of your friends who might be skipping that there will be a quiz on Wednesday. Fair warning.

Today, we will be discussing radiometric dating.

Naturally-occurring radioactive materials break down into other materials at known rates. This is known as radioactive decay.

Radioactive parent elements decay to stable daughter elements.

Radioactivity was discovered in 1896 by Henri Becquerel. In 1905, Rutherford and Boltwood used the principle of radioactive decay to measure the age of rocks and minerals (using Uranium decaying to produce Helium. In 1907, Boltwood dated a sample of urnanite based on uranium/lead ratios. Amazingly, this was all done before isotopes were known, and before the decay rates were known accurately.

The invention of the MASS SPECTROMETER after World War I (post-1918) led to the discovery of more than 200 isotopes.

Many radioactive elemtns can be used as geologic clocks. Each radioactive element decays at its own nearly constant rate. Once this rate is known, geologists can estimate the length of time over which decay has been occurring by measuring the amount of radioactive parent element and the amount of stable daughter elements.

Comments

[chasingangela]

Angela takes a seat and listens to the lecture.

[sensethevisions]

Phoebe comes in and takes a seat with Angela. She looks like she's doing better. She's still pale and looks tired, but she no longer feels like she's going to die from the flu.

[12parseckessel.livejournal.com]

Han signs in, slipping in just under the bell, and takes sporadic notes while doing a lot of clock-watching. He's out of his seat the second the bell rings and is gone.



[[ooc: let's do it under the right login, shall we?]]

[equalsmcsquared.livejournal.com]

Don't hurry off on my account. *Said good naturedly--she remembers high school.*

[ooc: I posted this first to Sara's journal. Don't feel bad. ;)]

[pure-blooddraco.livejournal.com]

Draco signs in and gets some coffee. He stayed away from the pumpkin pie because practically everything in the wizarding world was pumpkin-something and he was sick of it.

[auroryborealis.livejournal.com]

Rory signs in and takes her usual seat next to Draco, drumming her nails anxiously on the desk and glancing at hime sidelong every few minutes.

[pure-blooddraco.livejournal.com]

Draco stops taking notes and turns to look at Rory. "Are you alright?" he asks.

[auroryborealis.livejournal.com]

"Uh huh," Rory replies quietly, picking up her own pen and starting to take notes. "Just a little antsy what with it being my first day of classes after the whole thingy happened."

[pure-blooddraco.livejournal.com]

"Right. Well, I'm sure everything will be fine now that you know...everything is all cleared up." he trails off and clears his throat nervously. "So, that aside, did you have a good Thanksgiving break?"

[auroryborealis.livejournal.com]

Yup," Rory says shortly. "You?"

[pure-blooddraco.livejournal.com]

"Vegas was fun. I got to spend a lot of time with my girlfriend." he says "The city was pretty, I was amazed at what muggles can do without magic."

[auroryborealis.livejournal.com]

Rory nods and smiles in spite of herself. "Vegas is...colorful. I'm a bit sad I didn't get to go, actually."

[pure-blooddraco.livejournal.com]

"I wish you could have. I think Lily would have enjoyed your company." he smiles "I would have too, don't get me wrong."

[auroryborealis.livejournal.com]

"Yeah, I can imagine, considering from what An- from what I was given to understand, Lily and I would find common ground in our boyfriends enjoying themselves in strip clubs," Rory smirks.

[pure-blooddraco.livejournal.com]

"I did *not* enjoy myself in a strip club. Because if Lily found out I did enjoy myself I'd be dead." he winks at her "Besides, turns out Anakin is quite the ladies man. You wouldn't believe how many girls threw themselves at him."

[auroryborealis.livejournal.com]

"Doesn't surprise me. Anakin's a good-looking guy," Rory says appraisingly. "Though I thought I heard somewhere that he's supposed to stay celibate..."

[pure-blooddraco.livejournal.com]

"I heard about that too. But everytime we asked about it he got all monologue-y about how this was different. It was sort of confusing." Draco shrugs.

"Ah well, he's one of the lucky ones. We are a special few." Draco laughs.

[auroryborealis.livejournal.com]

Rory rolls her eyes. "I have a feeling that Anakin would be able to come up with reasons why every time it was, 'different,'" she laughs. She notices that Professor Sidle is writing something on the board, and begins taking notes again.

[ooc: Because ack, getting sucked into a meeting...]

[alchemic-bean.livejournal.com]

Edward signs in and sits down, taking his usual sporadic notes. He keeps randomly glancing out the window.

[bridge-carson.livejournal.com]

Bridge listens attentively to the lecture but, for once, does not take notes.

[conathon.livejournal.com]

Sawyer finds the lecture very interesting and takes a few detailed notes.

[aroseintime.livejournal.com]

Rose comes in, signs the roll sheet quietly and takes a seat.

[miss-thomasina.livejournal.com]

Thomasina signs her name to the class roster and takes her seat. She spends the remainder of the lecture taking careful notes in her exercise book.