Chris Rowan is a geologist specialising in the dark arts of paleomagnetism, and getting people to pay him to travel to exotic destinations for fieldwork. Having drilled up New Zealand during his PhD, he is now a post-doc at the University of Johannesburg. 
So I've been playing around a bit with my mini timescale, and it is now available in two flavours, the original, but improved, right to left orientation:
and the all-new left to right version, which I have to concede might indeed be 'better':
For those that want to use this on their own blogs, the EPS files I link to can be imported into programs like CorelDraw and Illustrator, so you can modify the red locator bar (and anything else) to suit before exporting an all-new jpeg.
As for this blog, which one do you prefer?
Update: In answer to Brian's question below, this chart was based on the information from the webpage of the International Commision of Statigraphy, specifically this page (you can also download a pdf chart here ).
Further update: Just to be clear, anyone who finds these figures useful is welcome to use them for any (non-commercial) purpose that they like. Attribution would be nice where practical, but I won't be sending in the faceless copyright zombies if you don't.
Comments
I like the present being on the left. Thanks for making, these I'm gonna download one.
Posted by: BrianR | August 8, 2008 11:48 AM
oh, one more thing ... should we put where the numbers are coming from? Is this the 1999 GSA timescale? As Kim pointed out in the previous thread, the numbers continue to be refined ... maybe it doesn't matter at this scale though.
Posted by: BrianR | August 8, 2008 11:52 AM
It's the ICS timescale, last updated in 2004 I think. I've added links above.
Posted by: Chris Rowan | August 8, 2008 12:05 PM
A minor request, if I may. The timescales are alright for learning names but they don't really put things in proper context (it looks like the Cenozoic makes up fully half of all of history!). If you have the time to make one more with the length of the periods in proper relation to one another I think that would be a great tool. Maybe it's a minor quibble, but I think such a scale would make a very important point about where we are in terms of Deep Time.
Posted by: Laelaps | August 8, 2008 1:05 PM
ahh ... okay, thanks for the links ... this is cool.
Posted by: BrianR | August 8, 2008 1:06 PM
Laelaps says: "it looks like the Cenozoic makes up fully half of all of history!"
It is in a log scale so, you're right, it does appear that way. Making a timescale that is ~500 pixels wide at a linear scale would not work. The entire Phanerozoic (550 Ma to now) would be only ~50 pixels wide. So any blog post dealing w/ the Phanerozoic (which would be a lot) would have to put a tiny little red line w/in that 50 pixels.
Maybe it needs to be very clear that it's not a linear scale and some link to a linear version that emphasizes how vast the pre-Phanerozoic history is.
Posted by: BrianR | August 8, 2008 1:45 PM
I prefer left-to-right, but then I'm an engineer. And as an engineer, I wouldn't mind if the time scale were logarithmic, not piecewise linear. You could then include Big Bang by extending the diagram a bit to the left.
Posted by: Lassi Hippeläinen | August 8, 2008 2:06 PM
Thanks Chris!
I prefer present to the right, but I've seen them both ways.
Posted by: Silver Fox | August 8, 2008 2:24 PM
Lassi says: "as an engineer, I wouldn't mind if the time scale were logarithmic, not piecewise linear."
Remember, the point is not to be mathematically rigorous about the scale but to produce an illustration that helps those who aren't familiar with the names of these time periods get to know them. What Chris has done nicely shows all the names in one diagram ... a diagram dealing with the absolute ages (whether it's logarithmic, linear, or whatever) would be useful in that sense, but not so much with regards to the names of the periods.
Posted by: BrianR | August 8, 2008 2:26 PM
Thanks Chris, a great help for those who - like me - ended up in Geosciences having never taken a single Geology class!
Posted by: Alessia | August 8, 2008 3:27 PM
As a total newbie on this blog, not sure if I should give an opinion or not... but for what it's worth, it makes more sense to me with the present on the left (although I can cope with it the other way round as well).
Posted by: Penny | August 8, 2008 3:42 PM
Harumph.
Vertical scale, oldest on bottom because of superposition.
(grumpy member of secret international cabal of historical geology profs...).
Seriously, though, a useful tool. I use a similar (vertical...) linear scale only PowerPoint slides when teaching Historical, and do a shift to a Phanerozoic-only scale when I hit the base of the Cambrian, and a Cenozoic-only when I cross the K/Pg.
Posted by: Thomas R. Holtz, Jr. | August 8, 2008 4:56 PM
I like the oldest on the left, youngest on the right, since I read a language which proceeds from left to right (but if you switched to vertical, I'd like the older on the bottom.
Log scale does make sense in terms of getting it all to fit -- is there such a thing as a "reverse log scale", so that the biggest part is the end with the older rocks? The youngest metamorphic episode I'm dealing with is 510 Ma, so for my blog, it would be helpful to arrange the numbers such that there was more room on the old end, less on the young end, but I don't know enough about how log scales work to make it myself, so I'll hope you suddenly think that sounds like a fun project and provide us one of those, and in the short term have downloaded this version, in case I need to use it in my blog. Thanks for going to the effort, and for making it available!
I'm guessing that the double tick-marks at 600, 60, 2, & .2 Ma have something to do with the fact that this is a log scale, and aren't indicating a gap in the scale, is that correct?
Posted by: R.M. | August 9, 2008 12:35 AM
R.M.: ask the cosmologists, and ye shall get:
http://www-visualmedia.fnal.gov/VMS_Site/gallery/stillphotos/1985/0100/85-0138CN.hr.jpg
It's 3 MB, but I'm not sure if any of it is useful for geology...
Those double ticks are where the time scale changes by one decade. (And now that I took a closer look, I think there is an error in the Pleistocene: one single tick too many.) That is a bit misleading, unless you are only interested in the names of the periods, but then all periods should be of equal length.
A vertical scale sounds good to me, too.
Posted by: Lassi Hippeläinen | August 9, 2008 3:27 AM
I definitely prefer the oldest on the left, newest on the right. The vertical old-on-the-bottom, new-on-top is good too, because it represents the way things literally stack up in nature.
But for nongeologists like me, new-on-the-left and old-on-the-right doesn't compute, because it looks as if time is going backwards. I have to stop and flip it in my head to understand it. I suspect that's the case for the lay public in general, who probably haven't come across more than a couple of new-on-the-left graphics.
Posted by: themadlolscientist, FCD | August 9, 2008 7:19 PM
I like, and prefer the oldest on left since that's the order I read in. Would you mind if I used it in classroom presentations? I promise to use a citation.
Posted by: Carlie | August 9, 2008 8:00 PM
When I TA'ed intro geol labs as a student, we made a linear 2m=1Ga scale and wrapped it around the room over the blackboard, door, upper walls, etc. All 9 meters of it. Of course, the Holocene was still thinner than a human hair...
Posted by: Lab Lemming | August 10, 2008 7:47 AM
I am an historian (public history -- labour and industry), but Dad was (is) a geologist. Having grown up with his travling monologue lectures on the geology of the American Southwest, I find this quite usefull. I do have one question though: when the hell did the Precambrian disappear and when the hell did the Hadean, Archaen and Proterozoic appear? (keep in mind, Dear old Dad graduated in 1962, well before the revolutions (plate tectonics and micropaleaontology) created the chaos and order of today).
Posted by: iambilly | August 10, 2008 3:39 PM
I do appreciate all the effort that has gone into this, but, if this is designed for the lay person to understand (deep time) then the scale has to be linear. Perhaps three scales, Cenozoic, Mesozoic+Palaeozoic, Precambrian (with some overlaps).
Oh, and old (left) to young (right).
Posted by: hypocentre | August 10, 2008 6:22 PM
It's always a juggling act to come up with an easy-to-use time scale. The ones I have on my site are simple colored HTML tables with no attempt to be graphical (fat Proterozoic/skinny Pliocene). One table just has the eons and eras, another has them plus all the periods, then I have more for the Precambrian, Phanerozoic, and each of the three "modern" eras going all the way down to the age level. The public just can't remember all these time periods
Your graphic version with its pseudolog time axis is quite elegant.
Posted by: Andrew | August 11, 2008 12:47 AM
Oh, I know why I like new on left ... that's how detrital zircon plots are typically shown!
From the comments above, it seems like the perfect time-scale figure for blog posts would actually have at least two versions, one that is not linear and is good for gettin' to know the names, the hierarchy, their order, and all that(this is a good skill to have!); and another that is linear to emphasize the deep time aspect.
Posted by: BrianR | August 11, 2008 1:02 AM
Carlie, you're quite welcome to use this - as is anyone else.
Posted by: Chris Rowan | August 11, 2008 7:59 AM
iambilly:
pre-cambrian got divided up once people started studying it and discovered that there were obvious changes. Part of this involved the use of radiometric ages to determine how old igneous and metamorphic rocks were, and decent radiometric geochronology started to take off in the 70's.
Posted by: Lab Lemming | August 13, 2008 9:19 PM