Jack and Jill
Jack and Jill
[Megan is watching as the two kids Jill (drawn as Science Girl) and Jack (with spiky hair) are walking by her. Jack has a pail in his hand.] Jill: Me and Jack are going up the hill to fetch a pail of water.
[Megan, standing back alone, calls out after them.] Megan: Okay, have fun!
[Beat panel.]
Megan: ...Wait. What the heck is going on with the hydrology around here?

" Jack and Jill " is a traditional English nursery rhyme. The rhyme dates back at least to the 18th century, one version even with 15 stanzas.
The first and most commonly known verse is the one referenced by Jill in the comic as she says the first three lines:
Jack and Jill went up the hill To fetch a pail of water. Jack fell down and broke his crown, And Jill came tumbling after.
The comic makes fun of the counterintuitive idea that Jack and Jill go up a hill to fetch water, because natural water sources like rivers and streams flow downhill, making them usually found in valleys rather than on top of hills. Thus it shouldn't be necessary to have to go up a hill to get water. Similarly, if the water is coming from a well, then building a well at the top of a hill seems an odd choice to Megan . The groundwater table stays at about the same level over smaller areas, so building a well on a hill would require digging further.
However, Megan is probably not aware that since groundwater tends to flow in a similar direction to the slope of the land, it is often considered safer to dig a well uphill from potential sources of runoff, such as outhouses, fields, or septic systems. In times when populations were more predominantly rural, and probably when the poem was composed, "Always dig your well uphill from the outhouse" was a well-known maxim. Moreover, since it takes more energy to bring water uphill from a well (especially in a pail), there is a long-term advantage to having wells higher than main residential areas, as opposed to lower. (This principle explains why water towers are used, even in cities.) Finally, artesian wells deliver water from confined aquifers, which can sometimes be as close to the surface at higher elevations as at lower ones. As an urban dweller, Megan probably gets water from city plumbing, and is not familiar with the principles of well placement that Jack and Jill grew up with.
This all said, the predominance of drawing Jack's and Jill's well at the peak , which is not the best place to put the well, makes Megan's (and Randall's) comment understandable. Alternatively, the nursery rhyme may refer to a dew pond (which is more likely to be at the peak than a well), another concept that Megan would not be familiar with, having not grown up in the English countryside.
The title text is Randall 's own version, a parody of this first verse, where the names have been switched in the first and last line:
Jill and Jack began to frack. The oil boosts their town. But fractures make the bedrock shake and Jack came tumbling down.
This version, which may explain why they went up the hill after water, connects the idea to hydraulic fracturing (colloquially "fracking") methods for oil and gas extraction. In these methods, highly pressurized liquids are forced into a given ground stratum (or layer). With enough pressure, the stratum starts to deform and crack. This allows potential gas and oil to flow more freely. The liquid used for fracturing usually also contains materials like sand or ceramics which, once the liquid is removed, will help to maintain the newly formed cracks so as to further allow the desired free movement of oil and gas.
A common side effect of this method is that water levels and presence at the surface might be modified. In this comic, water can now be found at the top of the hill. This goes against the usual laws of hydraulics, themselves subject to the laws of gravity, which indicate that water should go down through ground cracks. Thus water is usually found at the bottom of valleys or hills. But in the comic, fracking at the bottom forces the water up, thus explaining why the kids go get water up the hill, which, as Megan points out, is messed-up hydrology . Also, fracking may cause induced seismicity in the form of microearthquakes , as alluded to in the title text, which is the cause for tumbling down in the title text version.
Randall has previously composed another version of this poem, which was by mistake published in Five-Minute Comics: Part 4 .
Jack and Jill went up a hill To fetch a pail of water. Alas, that hill was San Juan Hill, And gruesome was the slaughter.
In this comic it is made clear that Randall did know that it is possible to have a well on top of a hill, as he has drawn just one of these in the second image. The well in 561: Well and more obviously in 568: Well 2 was also found on top of a hill, although it appears this well did not contain any water.
This is the second Wednesday in a row that Randall uses two children to make a reference to an environmental issue, the first being 1659: Tire Swing , about tire recycling . In the other comic one of the girls is Science Girl who looks like Jill in this comic, and this fits well with her knowledge of science, fracking, and needing to go up the hill after water...
[Megan is watching as the two kids Jill (drawn as Science Girl) and Jack (with spiky hair) are walking by her. Jack has a pail in his hand.] Jill: Me and Jack are going up the hill to fetch a pail of water.
[Megan, standing back alone, calls out after them.] Megan: Okay, have fun!
[Beat panel.]
Megan: ...Wait. What the heck is going on with the hydrology around here?
