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edit iowa coal mine 1936 historically iowa was a significant coal producer particularly the des moines river valley from coalville south much of the greater city of des moines area was mined boone and what cheer were important in the late 19th century in the 20th century the most important mines were farther south around albia centerville lucas and oskaloosa iowa coal tends to be too high in sulfur for modern applications and the last commercial mine closed in 1994 14 iowa has very limited natural gas and oil production 15 sioux quartzite edit although iowa s bedrock is generally younger in western parts of the state one exception is a small part of far northwest iowa where precambrian sioux quartzite bedrock is found in northwest lyon county sioux quartzite is a very hard rock of ruddy pink color used extensively in the region for road and railroad beds 16 sioux quartzite has been dated to have been laid between 1 64 and 1 76 billion years ago 17 geode half geodes edit geodes are found in southeast iowa and are the official state rock they consist of grey to pink cobbles within limestone that when cut or smashed open reveal a hollow crystal filled interior geodes are common around geode state park in henry county 18 landforms and topography edit this article has multiple issues please help improve it or discuss these issues on the talk page learn how and when to remove these messages this section includes a list of general references but lacks sufficient corresponding inline citations please help improve this section by introducing more precise citations november 2019 learn how and when to remove this message this section relies on a single source please help improve this section by adding citations to reliable sources unsourced material may be challenged and removed find sources geography of iowa news newspapers books scholar jstor november 2019 learn how and when to remove this message learn how and when to remove this message topography of iowa with counties and major streams landforms of iowa based on prior 1991 and calvin 1904 with major rivers and streams despite popular perception iowa is generally not flat most of the state consists of rolling hills prior 19 divides iowa into eight landforms based on glaciation soils topography and river drainage paleozoic plateau edit also known as the driftless area this region of scenic high relief landscapes includes such features as resistant bluff forming bedrock outcrops deep v shaped valleys caves springs and sinkholes glacial deposits and loess are thin or absent over most of the region des moines lobe edit barringer slough a remnant of the extensive prairie wetlands that once covered the des moines lobe often called the prairie pothole region the des moines lobe was glaciated up until 12 000 years ago during the wisconsin glaciation the area is marked by rolling terrain and ridges 20 historically this area was peppered with small interconnected swamps most of which were drained for farmland the iowa great lakes occur along the western edge of the des moines lobe southern iowa drift plain edit typical view of the southern iowa drift plain the southern iowa drift plain covers most of the southern half of iowa this is probably the most familiar landscape to travelers since most of interstate 80 in iowa runs through the sidp the classic iowa landscape consisting of rolling hills of wisconsin age loess on illinoian or earlier till the sidp is some of the most productive agricultural land in the us mississippi alluvial plain edit mississippi valley wetland near ft madison iowa generally level areas of stream terraces paleochannels backwater sloughs and oxbow lakes are found within the broad mississippi river valley loess hills edit the loess hills consist of very thick deposits of loess in far western iowa deposited during the wisconsin and illinoian periods highly eroded leaving stark beautiful golden hills loess hills east of mondamin iowa showing the transition with the missouri alluvial plain iowan surface edit northeast iowa is covered with eroded pre illinoian till with moderate loess formation frequently in the form of paha ridges muted relief except for steep rolling hills near river valleys and deeper valleys these picturesque hills are depicted in many of the landscapes of grant wood northwest iowa plains edit like the iowan surface the northwest iowa plains are rolling hills consisting of eroded soils developed since pre wisconsinan glaciation but with significant amounts of loess missouri alluvial plain edit perhaps the only truly flat region of iowa the missouri alluvial plain contains areas of terraces sloughs and oxbows its valley trench is not as deep as the mississippi river system and the missouri river is contained in a much narrower channel in iowa the eastern border of the missouri plains is the loess hills forming steep rounded bluffs climate edit further information climate change in iowa köppen climate types of iowa using 1991 2020 climate normals iowa has a humid continental climate throughout the state köppen climate classification dfa with extremes of both heat and cold the average annual temperature at des moines is 50 f 10 c for some locations in the north such as mason city the figure is about 45 f 7 c while keokuk on the mississippi river averages 52 f 11 c 21 snowfall is common with des moines getting about 26 days of snowfall a year and other places such as shenandoah getting about 11 days of snowfall in a year 22 spring ushers in the beginning of the severe weather season iowa averages about 50 days of thunderstorm activity per year 23 the 30 year annual average of tornadoes in iowa is 47 24 in 2008 twelve people were killed by tornadoes in iowa making it the deadliest year since 1968 and also the second most tornadoes in a year with 105 matching the total from 2001 25 iowa summers are known for heat and humidity with daytime temperatures sometimes near 90 f 32 c and occasionally exceeding 100 f 38 c average winters in the state have been known to drop well below freezing even dropping below 18 f 28 c iowa s all time hottest temperature of 118 f 48 c was recorded at keokuk on july 20 1934 during a nationwide heat wave 26 the all time lowest temperature of 47 f 44 c was recorded in washta on january 12 1912 27 iowa has a relatively smooth gradient of varying precipitation across the state with areas in the southeast of the state receiving an average of over 38 inches 97 cm of rain annually and the northwest of the state receiving less than 28 inches 71 cm 28 the pattern of precipitation across iowa is seasonal with more rain falling in the summer months virtually statewide the driest month is january or february and the wettest month is june owing to frequent showers and thunderstorms some of which produce hail damaging winds and or tornadoes in des moines roughly in the center of the state over two thirds of the 34 72 inches 88 2 cm of rain falls from april through september and about half the average annual precipitation falls from may through august peaking in june 29 climate data edit monthly normal high and low temperatures for various iowa cities f 30 city jan feb mar apr may jun jul aug sep oct nov dec davenport 31 30 13 36 19 48 29 61 41 72 52 81 63 85 68 83 66 76 57 65 45 48 32 35 20 des moines 32 31 14 36 19 49 30 62 41 72 52 82 62 86 67 84 65 76 55 63 43 48 31 34 18 keokuk 33 34 17 39 21 50 30 63 42 73 52 83 62 87 67 85 65 78 56 66 44 51 33 33 21 mason city 34 24 6 29 12 41 23 57 35 69 46 79 57 82 61 80 58 73 49 60 37 43 25 28 11 sioux city 35 31 10 35 15 47 26 62 37 73 49 82 59 86 63 83 63 76 51 63 38 46 25 32 13 climate data for des moines international airport iowa 1991 2020 normals a extremes 1878 present b month jan feb mar apr may jun jul aug sep oct nov dec year record high f c 67 19 78 26 91 33 93 34 105 41 103 39 110 43 110 43 101 38 95 35 82 28 74 23 110 43 mean maximum f c 53 4 11 9 58 7 14 8 74 6 23 7 83 9 28 8 88 9 31 6 93 1 33 9 96 2 35 7 94 4 34 7 91 3 32 9 83 3 28 5 70 4 21 3 57 8 14 3 97 4 36 3 mean daily maximum f c 30 9 0 6 35 7 2 1 49 2 9 6 62 0 16 7 72 4 22 4 81 9 27 7 85 6 29 8 83 6 28 7 76 9 24 9 63 4 17 4 48 3 9 1 35 9 2 2 60 5 15 8 daily mean f c 22 3 5 4 26 9 2 8 39 4 4 1 51 3 10 7 62 4 16 9 72 2 22 3 76 0 24 4 73 9 23 3 66 2 19 0 53 2 11 8 39 3 4 1 27 7 2 4 50 9 10 5 mean daily minimum f c 13 8 10 1 18 0 7 8 29 6 1 3 40 6 4 8 52 3 11 3 62 4 16 9 66 4 19 1 64 2 17 9 55 4 13 0 42 9 6 1 30 2 1 0 19 5 6 9 41 3 5 2 mean minimum f c 7 8 22 1 2 7 19 3 9 2 12 7 24 9 3 9 37 6 3 1 50 2 10 1 56 9 13 8 54 8 12 7 40 4 4 7 26 8 2 9 12 6 10 8 1 2 18 4 11 4 24 1 record low f c 30 34 26 32 22 30 9 13 26 3 37 3 47 8 40 4 26 3 7 14 10 23 22 30 30 34 average precipitation inches mm 1 08 27 1 34 34 2 17 55 4 02 102 5 24 133 5 26 134 3 82 97 4 17 106 3 18 81 2 78 71 1 91 49 1 58 40 36 55 928 average snowfall inches cm 9 4 24 10 2 26 4 4 11 1 2 3 0 0 2 0 51 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 1 3 2 7 6 9 7 9 20 36 5 93 average extreme snow depth inches cm 6 9 18 7 4 19 4 2 11 0 8 2 0 0 2 0 51 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 76 1 7 4 3 4 9 12 10 3 26 average precipitation days 0 01 in 8 2 8 4 9 5 11 5 12 7 11 7 9 5 9 4 8 2 8 6 7 7 7 8 113 2 average snowy days 0 1 in 6 9 6 3 3 1 1 0 0 1 0 0 0 0 0 0 0 0 0 5 1 8 5 6 25 3 average relative humidity 71 0 71 3 67 9 63 2 63 0 64 8 67 7 70 0 70 9 66 5 71 0 74 6 68 5 mean monthly sunshine hours 157 7 163 3 206 0 222 2 276 0 312 1 337 8 297 9 239 8 210 0 138 5 129 2 2 690 4 percentage possible sunshine 53 55 56 56 61 69 73 70 64 61 47 45 60 average ultraviolet index 1 2 4 6 8 9 9 8 6 4 2 1 5 source 1 noaa relative humidity and sun 1961 1990 36 37 38 source 2 weather atlas uv 39 water edit iowa annual rainfall in inches mississippi river alluvial plain from sidp bluffs north of kingston iowa as in most of the u s surface water in iowa is never safe to drink untreated contamination by agricultural runoff including nitrates herbicides pesticides and animal waste is common though the clean water act has helped municipal water supplies are typically heavily chlorinated this chlorine combined with high nitrate levels often give municipal water a strong smell and the limestone bedrock in much of the state causes hard water 40 some communities such as iowa city resort to additional carbon filtration and lime softening coagulation sedimentation to make the water more palatable 41 water treatment can be surprisingly effective des moines advanced filtration system has led to water quality ranked among the nation s best 42 jordan aquifer edit the jordan aquifer is the largest source of groundwater extending from northeast iowa to south central iowa and is ultimately the source of much of iowa s agricultural and industrial water in addition to pollution threats the aquifer is threatened by overuse in well source irrigation ethanol production and the diminishment of resupply caused by extensive field tilling the aquifer has dropped by as much as 300 feet since the 19th century resulting in dry wells the disappearance of natural surface springs and the diminishment of water quality 43 44 soils edit the nrcs divides iowa into 23 soil regions in general soils of southern eastern and western iowa are loess derived while soils of northern and central iowa are till derived most level areas of iowa have soils highly suitable for agriculture making iowa one of the most productive farming regions of the world 45 radon edit radon levels in u s showing iowa with some of the highest levels like most upper midwest and plains states radon is a common problem in iowa especially in areas with clay rich soils 46 radon is the highest in the southern and the western parts of iowa paleontology edit devonian fossil gorge edit floods in 1993 washed away all the soil and unconsolidated bedrock along the spillway of the coralville lake dam in johnson county exposing a rich collection of devonian age fossils from species such as ancient hexagonaria corals this area has been transformed into a visitors center where hikers can tour the bedrock unfortunately looters have illegally removed many of the better fossils 47 the june 2008 floods expanded the fossil bed floor and removed some of the weathered overburden 48 dinosaurs edit jurassic and cretaceous bedrock in western iowa have potential to contain dinosaur remains and in nearby parts of nebraska hadrosaurid duck billed ornithopod dinosaur remains have been recovered in cretaceous bedrock similar to that of iowa the deep loess that covers much of western iowa typically conceals the bedrock limiting opportunities to finding dinosaurs to mining and quarrying operations 49 paleofauna edit archaeological and paleontological sites in iowa have produced an extensive collection of pleistocene and holocene animals these have been used to reconstruct past environmental conditions in the midwest 50 some of the earliest paleoclimatic reconstructions of the midcontinent were made from iowa collections such as the cherokee sewer site 51 a pleistocene giant sloth is under excavation along west tarkio creek near shenandoah iowa three individuals of megalonyx jeffersonii or jefferson s ground sloth have been identified so far including one adult and two juveniles of different ages 52 53 notable iowa geologists edit samuel calvin 1840 1911 was iowa s first systematic geologist who helped to make the first bedrock and landform maps of iowa as well as lead geological research throughout the state 54 calvin hall at the university of iowa is named for him clair cameron patterson 1922 1995 developed the lead lead dating and calculated an age for the earth of 4 55 billion years a figure far more accurate than those that existed at the time and one that has remained unchanged for over 50 years charles rollin keyes was also an early iowa geologist who helped map the soils and bedrock of southeast iowa he with calvin was a founder of the iowa geological survey notes edit mean monthly maxima and minima i e the expected highest and lowest temperature readings at any point during the year or given month calculated based on data at said location from 1991 to 2020 official records for des moines kept august 1878 to august 1939 at downtown and at des moines international since september 1939 for more information see threadex references edit prior geology of iowa iowa s earth history shaped by ice wind rivers and ancient seas archived 2009 04 16 at the wayback machine manson earth impact database planetary and space science centre university of new brunswick fredericton retrieved 2022 10 04 iowa s manson impact structure archived 2008 06 16 at the wayback machine vastag brian 18 february 2013 crater found in iowa points to asteroid break up 470 million years ago washington post retrieved 19 february 2013 1 2 geological survey ancient meteorite crater sits below decorah cedar rapids gazette 5 march 2013 retrieved 6 march 2013 us geological survey iowa meteorite crater confirmed retrieved 7 marc...