2007-05-24 05:29:25 · 5 answers · asked by dharahni 2 in Science & Mathematics ➔ Earth Sciences & Geology
What I mean is, will a compass respond to the presence of basalt?
2007-05-25 13:05:54 · update #1
dharah,
this is an excellent question. bassalt formations are, odly enough, responsible for many people getting lost out in the wild while on a hunt, hike, or whatever they are there for. The compass will definitely respond to bassalt formations which have a high enough iron content throwing off a compass needle even a couple degrees; but not all bassalts are created equally. iron content varries widely from one basalt formation to another. those who are following a map and compass to get to a particular destination have found themselves miles from their desired goal location, despite their expertise with a compass and a map!
So the next time you're out hiking and using a map and compass to guide your way, take along a good USGS 7½' geologic quadrangle (with topo) with you so you can use dead reconing as well. That way you won't get lost. Not only that, but if you can read the geologic coding, you can tell if you're entering into a basalt laden area and be on the lookout for compass deviation.
good luck...dont get lost!
2007-05-24 05:38:09 · answer #1 · answered by Tommy 3 · 0⤊ 0⤋
Basalt DOES have weak magnetism. That is why is creates magnetic anomalies when measured with sensitive geophysical equipment.
It will not respond to a compass, but a compass will respond to basalt. Surveying with a compass across basaltic terrain definitely influences the compass needle, but you have to be making very accurate directional measurements to notice it sometimes.
2007-05-24 09:17:59 · answer #2 · answered by asgspifs 7 · 1⤊ 0⤋
Iron in its pure state is magnetic, but its compounds are either non-magnetic or feebly magnetic. For example, steel is practically non-magnetic.The mafic minerals in basalt, (which are major constituents of the rock) are mostly silicates and hence non-magnetic. Some accessories like rutile etc. are, however, weakly magnetic.
I have taken traverse in many basaltic terrains and never faced any problem with my compass's functionality. The problem described by Tommy appears to be due to some other reasons, like presence of some strongly magnetic minerals like magnetite.
2007-05-24 06:00:12 · answer #3 · answered by saudipta c 5 · 1⤊ 0⤋
Yes, when basalt cools, magnetite, an iron mineral will crystallize and will retain the magnetic direction of the earth's magnetic field and will be magnetic. This creates magnetic anamolies as the magma cools in magnetic fields that change over time.
2007-05-24 07:00:43 · answer #4 · answered by JimZ 7 · 1⤊ 0⤋
Last time I checked it was the compass that responded to the rock.
2007-05-24 07:22:05 · answer #5 · answered by Anonymous · 0⤊ 0⤋