Answer: A couple of questions about Polynesia! (Why so long? What are those clear patches?)

I'm back in Silicon Valley... but missing Polynesia.. 

If you get the chance to visit, you should.  If the predicted sea level rise happens, many of these islands are going to be submerged.  That's tragic, but what's worse is that the memory of these special places will vanish from the common culture.  
But before solving the climate change problem, let's focus in on our Challenges.  

1.  In researching the dates of initial colonization of Polynesian islands, I noticed a VERY strange incongruity.  Look at the map below.  The blue pins are all island nations that were first colonized around 1000AD.  The red pins (to the left of the long green line) were all colonized around 1000BCE or before.  What happened here between 1000BCE and 1000AD?  Why are the all of the blue pins MUCH later than the red pinned locations?  It's not that far from Samoa to Niue, why didn't anyone colonize that island until 900AD or so?  Generally--why didn't the Polynesians go beyond the green line for a very long time?  

This sounds simple enough... but it turns out to be a bit of a contentious issue.  As I discovered, there's a bit of debate about the dates I show above.  Getting a definitive answer to this is probably a PhD's thesis worth of work (and there are people doing exactly that!), but let's see what we can do with our SRS skills.  

I started my research with this query: 

     [ Polynesia colonization dates ] 

which gave me this SERP: 

As you can tell, I opened up several tabs in parallel to get a quick sense of the breadth of opinion on this: 

The first tab is from Hokulea.com (a Hawaiian cultural education site), the second is from Wikipedia, 3rd is from Phys.org (a science news site).  Others I opened were from other science journalism sites.  

By reading about 10 such sites, I quickly learned that there's some disagreement about the exact dates for Polynesian island colonization.  The root of the discussion is about the accuracy of the methods used in previous research.  (There's a big discussion about the accuracy of the reported 14C measurements.)  

But after reading through many of these reports, the overall pattern still holds.  The dates might be off by anywhere from 75 - 150 years, but the overall story remains the same.  The precusors of the Polynesians moved from somewhere in southeast Asia to colonize the islands around Melanesia, stopping sometime around 1000BCE.  (This model of expansion is supported by genetic, linguistic, and archaeological data. See: Wikipedia article on Polynesia; Proc. National Academy article about Polynesia colonization;  Stanford summary of dates)

Here's a visual map of this (modified from the PNAS article): 

Expansion migration out of West Polynesia (blue area),  There was a first expansion to the Society Islands between A.D. ∼1025 and 1121 (orange), and a second expansion to the farther islands between A.D. ∼1200 and 1290 (yellow area).

While this is confirmation (and consistent with what I'd found already), as I was reading, I kept finding the phrases "Polynesian pause" and "Polynesian expansion."  Both seemed to describe what I was looking for.  

As we know, finding a common phrase that describes what you're searching for is an incredibly valuable thing.  

Armed with this, I did two searches.  One on Scholar and one on Books, both with the same search query.  NOTE that this isn't a search for a synonym (such as "Polynesian OR Tahitian"), but a search for two very different phrases.  I'd be happy with either phrase being in the document. 

     [ "polynesian pause" OR "polynesian expansion" ] 

A search on Google Scholar has pretty good results for this search combined search. 

Likewise... 

After reading through a bunch of these hits--both books and scholarly articles--I had a newfound appreciation for the difficulty of tracking the movement of people across thousands of years and thousands of miles.  (The biggest surprise was the relevance of the book "Microbial Pathogenomics," which turns out to suggest a way of tracking expansion by tracking the movement of a distinctive gut bacteria, hpEastAsia, across the islands of Polynesia by looking at the bacterial populations of their current residents!)

But the original Challenge was "WHY was there a thousand-year-long pause in the migration?"  

What did I find?  

Lots of speculation--wild guesses and hypotheses.  Nobody, it seems, knows WHY this happened.  But one paper on this topic stands out as the current dominant hypothesis.  "From west to east: Environmental influences on the rate and pathways of Polynesian colonization"  (by Alvaro Montenegro, Richard T. Callaghan, and Scott M. Fitzpatrick; The Holocene 24.2 (2014): 242-256) uses a combination of weather models (including common Pacific winds and currents) and departures from different points in central Polynesia show that ...

".. the eastern boundary of West Polynesia, the limit of the initial colonization pulse, is marked by a discontinuity in land distribution, where the distances travelers would have to cross in order to reach islands further to the east become significantly larger. At the same time, in West Polynesia, the frequency and intensity of winds favorable to eastward displacement decrease continuously from west to east.... Voyaging simulations show that intentional eastward voyages departing from Tonga and Samoa, when undertaken with vessels capable of sailing efficiently against the wind, afford a viable route toward several island groups in East Polynesia, with trips starting in Samoa having a higher probability of success." 

Hidden in that complex language are a couple of ideas.  (1) The winds and currents at the West/Central boundary form a kind of natural barrier to eastward expansion.  (2)  It's hard to cross that barrier until you have watercraft that can sail into the wind. 

Did it take a millennium to develop ships that can sail into the wind?  Maybe.  And maybe it took that long to both develop the ship technology AND grow a set of people who were willing to make those blind voyages into the unknown in search of other lands.  It's possible that the upwind sailing tech was developed not long after arriving at the eastern edge, but that there wasn't a tradition of making those voyages. At this point in history, it's hard to know.  As I can do is point to sources that make these speculative suggestions.

2.  As we're sailing from place to place, it's not uncommon to see large patches of water without any ripples on the surface.  It's something you see nearly everywhere--it's a common effect on lakes, ponds, and oceans.  But what causes these ripple-free regions on the water?   (See below for an image that has a large Y-shaped blank area in the middle. What causes this?)  

To answer this Challenge, I tried a lot of variations on what I thought would be a reasonable query: 

     [ lines of flat water ] 

     [ areas of calm water on ocean ] 

     [ regions no waves ] 

And so forth.  I found that some search terms (e.g., "wavelets") added an entirely new (and off-topic for me) dimension, so I learned to avoid those terms. 

After a few tried like this (mostly with unhelpful results), I switched to Image search, hoping to recognize an image that looked like what I wanted and learn from that page what this might be called.  When I did this search:  

    [ lines of calm water on ocean ] 

I finally found a picture that looked like what I'd been searching for... 

This article called them Langmuir Circulation lines.  Searching a bit for that taught me that they're "a series of shallow, slow, counter-rotating vortices at the ocean's surface aligned with the wind. [These form] .. when wind blows steadily over the sea surface."  Where the long, wind-caused vortex hits the surface, that has a calming effect on the texture of the water. And that's possible... but I hadn't thought to measure which way the wind was blowing when I took the photo!  (I will next time.)  

As I looked more, I found that Langmuir circulation often also produces long "wind rows" of form on the edges of the circulation cells.  (See below.) 

Is this the same phenomenon?  Quite possibly.  The diagnostic test would be to see if the wind is blowing in the same direction as the lines of foam.. or the quiet area seen in the other images.  

As SRS reader Unknown pointed out, there are probably multiple reasons for these quiet lanes in the sea.  

But for the moment, I'll go with Langmuir Circulation lanes... and remember to test this hypothesis by noting the wind direction! 

Search Lessons  

1.  Take note of special terminology that precisely describes your topic.  As I noted when reading through all of the Polynesian articles, those two phrases "Polynesian Expansion" and "Polynesian Pause" seemed to pop up often.  By searching specifically for those two phrases (in Google Books and Google Scholar), I was able to find a bunch of high quality resources.  Take note of repeated phrases like this--they can be the key!  

2.  Realize that some simple-to-ask questions might not have simple, short answers--ESPECIALLY "why" questions.  Getting a definitive answer to "why did the Polynesian pause suddenly stop?" is tough.  It's easy to find ideas, but getting to a high quality proof behind the why is probably not possible.  (Or at least it's really not simple!)  

3.  Switching to a different medium can help.  In the "lines of calm water" Challenge, it was faster to look at the image search results rather than read all of the text that might be difficult to understand.  Visual confirmation can often get you to the right resources faster than anything else.  Don't forget about the value of the visual! 

4. Use parallel browsing and browsing-in-depth to organize your searching.  It's a handy technique to know... and can simplify your searching!  

Thanks for reading (and playing) along.  This wasn't simple.  

Next week I have two more questions from my recent travels.  I'll post those a week from today (next Thursday) instead of Wednesday.  Don't panic!  All is well (but busy) in SearchResearch Land! 

Search on!