The best way to bond with your family is over food! Try this traditional Mexican dish while learning about geology. As you prepare the ingredients and assemble your enchiladas, think about the different ways the rocks and fossils of the Florissant formation are layered to form what we see today atFlorissantFossilBeds.
For this activity,you’ll need parentalguidance andsupervisionbecausethis recipe involves the use of a stove.Feel free to substitute any of the ingredients for whatever you have at hand. You can always improvise the recipe to accommodate yourtaste. Thisrecipe yields20 enchiladaswith a total cookingtime of about40 mins.
Geology: noun; an earth science that studies Earth's physical structures, history, and processes.
Sedimentary: adjective; arock type that forms from fragments of pre-existing rocks, sediments, or organic materials at Earth's surface.
Strata: noun; layer (stratum) or sequence of rock layers that are deposited on earth's surface.
Stratigraphy: noun; a branch of geology that studies the order and position of strata or rock layers and their relationship to the geologic time scale.
Geological formation: noun; a distinctive unit of rock that can be distinguished from the surrounding rock units.
Stratigraphic column: noun; a representation of the rock units in an area that describes the sequences of sedimentary strata and their vertical position.
Fossils: noun; preserved remains, such as skeletons, impressions, and traces of once-living organisms.
Batholith: noun; large mass of intrusive igneous rock that forms from a slow cooling body of magma beneath earth's surface and is larger than 100 square kilometers.
Granite: noun; a coarse-grained intrusive igneous rock.
Caldera: noun; a large volcanic crater that formed after a large eruption causes the mouth of the volcano to collapse.
Tuff: noun; A type of porous (from air pockets) rock that formed from volcanic ash fusing together.
Conglomerate: noun; coarse-grained sedimentary rock consisting of rounded fragments (> 2 mm) in a fine-grained matrix.
Pumice: noun; light and porous volcanic rock that forms as a gas-rich glassy lava cools rapidly.
Debris flow: noun; moving mass of soil, debris, or fragments of rock traveling from high and steep slopes.
Lahar: noun; volcanic mudflow that forms when accumulated volcanic ash on the side of a volcano mixes with heavy rainfall.
This stratigraphic column shows the rock strata seen at Florissant Fossil Beds.
NPS
Learn about the specific rock layers described in the stratigraphic column for Florissant Fossil Beds, such as the Florissant Formation which contains various types of fossils. This is done by using food ingredients for enchiladas that represent each rock layer described in the stratigraphic column as pictured here.
Stratigraphy is a branch of geology that studies the order and position of strata or rock layers and their relationship to the geologic time scale. The law of superposition, which is a major principle in stratigraphy that applies to a sequence of sedimentary rock layers. This principle states that older rocks layers are at the bottom and younger rock layers are on top. These distinct rock sequences or rock units form a geological formation.
Geologists create stratigraphic columns through observing and describing the vertical position and thickness of rocks layers in an area. Stratigraphic columns show sequences of strata to understand relative ages based on vertical position: older rocks on the bottom and younger rocks on top.
Stratigraphic column illustrating how the ingredients in enchiladas correspond to the rocks layers of Florissant Fossil Beds, going from oldest at the bottom to youngest at the top.
NPS
Fossils and their association with specific rock strata has led to an understanding of the geological timescale and the relative ages of fossils.
At Florissant Fossil Beds National Monument, geologists have constructed a stratigraphic column of the Florissant Formation to understand the sequence and deposition of geologic events that occurred in this area over 34 million years ago.
The Florissant enchiladas is a visual and delicious representation of the rock units described in the Florissant Fossil Beds stratigraphic column. The Florissant Formation itself describes the sedimentary and volcanic rock layers formed from the ancient lake, stream, and volcanic deposits and contains various types of leaf, insect, fish and mammal fossils.
You'll be comparing these rock layers to the food ingredients for enchiladas as pictured.
The oldest unit in the area is the Pikes Peak Granite, which formed approximately 1 billion years ago. This intrusive igneous rock is part of a structure called a batholith, which forms from a slow cooling body of magma that solidifies beneath earth's surface. This rock unit became exposed at the surface during the uplift of the Rocky Mountains. About 37 million years ago, a caldera located roughly 50 miles west of Florissant near modern Mt. Princeton, erupted a superheated cloud of ash that settled to the ground and welded together forming the Wall Mountain Tuff.
Within the Florissant Formation are the following units: Lower Shale Unit, Lower Mudstone Unit containing the stream and lahar deposits, Middle Shale Unit, Caprock Conglomerate, Upper Shale Unit, and the Upper Pumice Conglomerate. This formation begins with the creation of Ancient Lake Florissant, which was created when a lahar dammed a stream. Due to the nearby volcanic activity, the lake began filling with volcanic ash, and the lahar dam became breached creating a stream valley allowing for stream deposits. The stream valley became flooded behind another lahar to form the lake again. Layers of ash, clay, and diatom mats accumulated in the lake and volcanic ash eruptions continued. These layers contain many of the leaf and insect fossils. Another large lahar flowed into the lake stirring up the sediment; however, the lahar didn't fill the lake entirely, so more volcanic ash eruptions deposited into the lake led to the formation of more shale layers. Lake Florissant disappeared when a huge volcanic eruption covered the area in pumice.
Supplies Needed
Cooking Supplies *To cook and prepare the enchiladas, parental supervision is required at all times.
Stove
Cooking tools; as many pots, pans, knife and utensils as needed
Blender
Ingredients
Feel free to substitute any of the ingredients with what you have at hand. You can always improvise the recipe to accomodate your taste and preference. This particular recipe yields 20 enchiladas with a total cooking time of about 40 minutes.
8 oz ground beef or plant-based 'beef' or shredded chicken, based on preference (fossil plants in Lower Shale Unit).
Cooking oil.
Seasonings - salt, black pepper, ground garlic, and your favorite spices.
2 small tomatoes, diced (fossilized mammal bone and teeth fragments in Stream Deposits).
Half an onion, diced (fossilized mammal bone and teeth fragments in Stream Deposits).
2 small potatoes, diced (petrified stumps in Lower Mudstone Unit).
2 small carrots, diced (Lower Mudstone Unit).
Optional - add according to preference
Almonds, blanched and chopped(fossil insects in Middle Shale Unit).
Raisins, whole (fossil insects in Middle Shale Unit).
For toppings - add according to preference
Lettuce, chopped (fossil fish in Upper Shale Unit).
Queso fresco, crumbled (Pumice Conglomerate).
For Red Chile Sauce:
Represents the volcanic mudflow deposit.
6 dried chiles
1 chile Pasilla
5 chiles California
4 tbsp sesame seeds
3 whole cloves
1 clove garlic
2 tbsp white vinegar
2 1/2 cups leftover beef or vegetable stock
2 squares authentic Mexican chocolate
Remove the seeds from the dried chile peppers.
NPS / Astrid Garcia
Directions
Prepare your Ingredients
Peel potatoes and carrots then rinse vegetables.
Dice/cube potatoes, carrots, tomatoes, and onion.
To prepare the almonds, heat them up in a pan to remove the outer skin and then chop into smaller pieces or purchase already blanched almonds.
Remove seeds from the chiles (Pasilla and California chiles).
Boil the potatoes and carrots in a pot of water, and ground beef in separate pot. Strain the potatoes and carrots then sauté chopped onions, tomatoes and seasoned ground beef in an oiled skillet.
NPS / Astrid Garcia
Meat and Veggies
On the stovetop, cook on low to medium heat and make sure the vent fan is on.
In a pot of water, add diced potatoes and carrots to boil until tender then drain.
In a separate pot, boil water then add ground beef or plant-based 'beef' or chicken until fully cooked.
Set aside leftover beef or chicken or vegetable stock if preferred for red chile sauce.
In a pan or skillet, add cooking oil to sauté diced onions then add diced tomatoes after onions are sauteed and clear in color.
Add the boiled ground beef or shredded chicken to the sauteed onion and tomato then cook altogether for several minutes and season.
Combine your vegetables and ground beef together with chopped almonds and whole raisins for an extra crunch and sweetness.
NPS / Astrid Garcia
Add the chopped almonds and whole raisins, boiled chopped potatoes and carrots and mix with the rest of the meat filling.
Leave on very low heat to keep the meat filling warm.
Making the red enchilada sauce. Don't forget to toast the red chiles and sesame seeds!
NPS / Astrid Garcia
Red Chile Sauce
On the stovetop - low heat;
On a comal, heat up the chiles until slightly toasted, do not burn!
Toast the sesame seeds.
Once the chiles and sesame seeds are toasted, add to a blender with cloves, garlic, chocolate, vinegar, and your leftover stock.
Blend until smooth and make sure the sauce isn't too thick! If so, then add more stock.
Assembling the enchiladas.
NPS / Astrid Garcia
Assemble the Enchiladas
On the stovetop - medium heat;
Heat up tortillas on oiled comal.
Once the tortillas are heated, roll up the meat filling containing the tomatoes and onions with the boiled potatoes and carrots, almonds and raisins (optional) into each tortilla that's dipped in the red chile sauce.
This part can get messy, so you can dip one side of the tortilla then cover the other side in the red sauce after rolling the tortillas.
Make sure to not overfill each one!
Add extra red chile sauce on top.
Put your lettuce and cheese toppings on your enchiladas then enjoy!
NPS / Astrid Garcia
Add chopped lettuce then crumbled queso fresco on top.
Before you dig in, place your enchilada on a plate. Use a fork to cut off a piece and examine what the cross section view of your enchilada looks like. Can you relate the layers of your enchilada to the rock layers seen in the stratigraphic column?
Eat and enjoy a homecooked meal with your family!
Reflection
Answer the following questions to assess your understanding of the sequence of deposition of the rock layers at Florissant Fossil Beds.
Which layer is the oldest and why?
Hint: Think about the Law of Superposition
Based on the fossils that are found in the Florissant Formation, what kind of environment do you think existed at the time of deposition?
What type of modern environment would sustain the modern relatives of the fossils found here 34 million years ago?
Relate each rock layer to a geologic event that occurred in Florissant Valley.
The oldest layer is the Pikes Peak Granite (1 billion years old), then the Wall Mountain Tuff (36.7 million years old) because it is at the base indicating it existed before everything else that was deposited on top.
The insect, fish, plant and mammal fossils found here indicate that this area was subtropical and there was a lake and forest here preserved because of the nearby volcanic activity.
Modern relatives of the fossils found here are in subtropical environments like a humid forest and freshwater lake. To learn specifically about some of these modern relatives and where they're found, read this Map Activity.
From oldest to youngest:
Pikes Peak Granite - uplifted magma pluton, Wall Mountain Tuff - collapsing caldera that erupted huge cloud of superheated volcanic ash.
Lower Shale Unit - formation of Ancient Lake Florissant, which was created when a lahar dammed a stream.
Lower Mudstone Unit - lake began filling with volcanic ash and the lahar dam became breached creating a stream valley allowing for stream deposits.
Middle Shale Unit - Stream valley became flooded behind another lahar to form the lake again. Layers of ash, clay, and diatom mats accumulated in the lake and volcanic ash eruptions continued. These layers contain many of the leaf and insect fossils.
Caprock Conglomerate - Large lahar flowed into the lake stirring up the sediment.
Upper Shale Unit - The lahar didn't fill the lake entirely, so more volcanic ash eruptions deposited into the lake led to the formation of more shale layers.
Pumice Conglomerate - Lake Florissant disappeared when a huge volcanic eruption covered the area in pumice.
