Logging tasks
- Visit the cache location. Let me know who you are submitting answers for, please try and log close to when you submit your answers.
- Is there a lot of gas chambers in the rock. Does it appear to have flowed or been thrown together?
- If it flowed, does it appear to be a smooth flow, or slower pressed flow? (like modeling clay)?
- Based on those two what kind of lava may it have been?
- What colors do you see, and what does that tell you about this lava?
Intro
I have though of this for some time. Mulling it over. The rock was retreved from Iceland, because spanish fork was setteled by people from Iceland. I have thought about it also because it is DrJays first cache, plus this week he becomes the cacher with the longest streak of 10+ years.
The real intro Lava
Scientists and geologists find out quite a bit from lava. Below are some of the different types and some info about them
Block Lava
This type of basaltic lava forms with very few gaseous bubbles. The silica content is fairly high and the temperatures tend to be lower than other types (2012° F). Because of less gasses, it tends to have a smooth, glossy surface. It creeps slowly and is very dense.
A'a
This is Hawaiin for hard on the feet. The lava flows of these have very rough and jagged survaces. It is more viscous than other types and flows slowly. Moving like a mass of broken rubble. The surface cools, and breaks up as it moves, then never softens again. So it is a mass of sharp, jagged edges. Those flows are pretty much impassable to those on foot, and can destroy hiking boots. The temperiatures tend to be about 2100° F
Cinders
In the early stages of a basaltic eruption, lava his highly charged with gases. As it approaches the surface and pressures drop, the gas expands raplidly, pushing the materual upward. An explosion takes place throwing it out. The lava cools rapidy and fall to the surface. Thes pieces tend to be a few mm it size to baseball size. They build up and create a cone around the volcano. The temperatures are around 2170° F
Pahoehoe
Is a smooth lava. It takes is name from the Hawaiian word for "ropy". Parhohoe lava flows are highly liquid, and flow easily. The surface of the flow cools and forms a thin crust, and the flowing lava below it drags it along, forming a layer that looks like ropes or coils. The temperatures of this are also very high 2170° F with a lower amount of gasses than cinders. Many more gas voids will be in these.
Colors
Most often the color of the rock is black. Basalt itsef is very black in color,. However sometimes when exposed to a large amount of gasses or other minerals from a volcanic vent you can get a red color from iron oxides, greens from olivine, and yellows from sulfer.