This lesson is a lab in which students take on much of the material they've worked on since the start of the unit and really begin to apply it. Students learn what unconformities are, and then get some lab time to "reverse engineer" much of what has happened in the geologic past.
[Note: Unlike most of my lessons, there are no embedded comments in this lesson, as it comes from an alternate resource. If you would need to access the resource in its entirety in a Word document, you can do so here: Making A Geologic Sequence [Lab] (Whole Lesson). Additionally, if you would like all of the resources together in a PDF document, that can be accessed as a complete resource here: Making A Geologic Sequence [Lab][PDF]. Finally, students may need their Earth Science Reference Tables [ESRT] for parts of the lesson (a document used widely in the New York State Earth Science Regents course) as well.]
Students come in silently and complete the (attached) Do Now. After time expires (anywhere from 2-4 minutes depending on the type of Do Now and number of questions), we collectively go over the responses (usually involving a series of cold calls and/or volunteers), before I call on a student and ask them to read the objective out loud to start the lesson.
As a general note, the Do Now serves a few purposes:
The Introduction & Vocabulary is an important topic in that it introduces some key vocabulary that they'll see (and use) in the lab, but it also give students the proper framing for how to proceed together when working in teams. Looking at the first page of the attached resource (posted above), we read the Introduction part together as a class. We then collectively define the two vocabulary words: unconformity and uplift.
Unconformities are buried erosional surfaces that usually follow a set pattern of: deposition - uplift - erosion - subsidence/burial. They are represented in geologic cross-sections by the "jagged" line separating rock strata. Uplift is a phenomenon covered previously, but it is vertical elevation of the crustal surface as a result of tectonic or geologic forces. This often exposes previously subterranean rocks on the surface, allowing the natural processes of weathering and erosion to take place.
The procedure for this lab is simple, but since this is the first time students get to sequence geologic events for themselves, they need to think critically about how they're going to proceed. For example, a question I always pose is:
"Where are you going to start?" - "Should you start from the most recent geologic event and work your way back?" (applicable via superposition), "... or should you start from the oldest event and work your way to the most recent?"
Generally, I let students decide (and they oftentimes change their minds), but if a group is particularly struggling, I generally find it easier to perform the latter - start from the oldest event and work your way to the most recent.
Since the Geologic Cross-Sections are meant to be done in only one period, there are only three (3) for them to complete. The first one if fairly straightforward, while the second and third cross-sections are generally more complex. [Note: See reflection in this section for more information on student groupings]
Under the 'Event' columns in the table, students should sequentially describe what is happening. For example, in the first cross-section (page 3 of the resource) the first event would be "Deposition of Conglomerate". Note that students can utilize their Earth Science Reference Tables [ESRT] [Page 7] for rock symbol keys.
Generally, students are given time to transition into their lab groups and work these out together. I go around and lend assistance if I see that students are missing a layer (they sometimes are unaware of the unconformities), or to offer a suggestion if they're really stuck. If they're finished before all the time in this section has elapsed, I let them begin work on the Discussion section (see below for resource).
As noted in the previous section, immediately after student groups are done, I ask them to start up on the Discussion section, as it has some summarizing questions for them to reflect on the laboratory activity. [Note: Unlike most of my other lessons, there is no exit ticket associated with this lesson.] I generally give them the bulk of remaining class time to finish up, although in the last few minutes, I have students self-assess on the attached Rubric at the end.
[Note: Depending on the day and class type, I sometimes have them either grade themselves, I grade them, or I ask a laboratory partner to grade another (i.e. "pass this to someone across from you to evaluate your lab performance today.") Given that this is a fairly regular occurrence in my classroom, this usually happens relatively quickly (under two minutes), although you may want to allot more time if you decide to do something similar for your class.]
Given that there are no necessary materials needed for this lab outside of the normal printed resources, clean up is usually quick, and only involves having the students put their desks back into a normal classroom arrangement and preparing their desks for transitioning out of the room.
In the last minute or so, I do utilize the same procedure I do on non-lab days, which is to ask the students time to think about their self-mastery of the objective (which is posted on the whiteboard), through some guided questions:
Once I take 2-3 individual responses (sometimes I'll ask for a binary "thumbs up/thumbs down" or something similar), I have students leave once the bell rings.