Dr. Sidney White: Advisor

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Ohio State University

THE MANY FACES OF MADAM PELE

Senior Thesis BY GERALD A. DERRYSHIRE

Submitted in partial fulfillment of the requirements leading to a Bachelor of Science degree in

GEOLOGY Dr. Sidney White: Advisor

Winter Quarter 1970 SLIDE 1 Madam Pele, so called by the natives in a mixture of res- pect and faailiarity, is described as a revengeflll ~~oddess, taking care of her friends and destroying her enenies. The legend of this fire goddess revolves around her search for a hone, visiting first one island and then another. Her search is preserved in the crumbling remains of extinct volcanoes, her destination revealed by the fiery eruptions of Kilauea. Many residents in the vicinity of her home . will testify that they have seen her in the form of an old woman prior to her display of awesome fury along Kilauea's flanks; however, when her activity is confined to the crater itself, she is described as a youthful woman of great beauty. The accounts of this myth provide the legendary foundation of the Hawaiian Islands and these islands reflect..."The ?any Faces of Madam Pele".

SLIDE 2 THE EL4NY FACES OF MADAM PELE Photography and Story by

Gerald A. Derbyshire 1970 SLIDE 3 The Hawaiian Islands are a chain of shield-shaped basaltic domes built over a fissure 1600 miles long in the ocean floor. Tiny dots in the isolation of the central Pacific, the islands are actually the tops of these shield-shaped domes, which, perhaps, constitute the greatest mountain

-1- range on earth, built up from the ocean floor by thousands upon thousands of volcanic lava flows with an average thickness of ten feet. The average depth of the floor of the ocean around the island chain is about 15,000 feet. There- fore, the lowest of the islands are mountains nore than 15,000 feet high and Wauna Kea, on the island of Hawaii,

rises more than 30,000 feet above its base. It is the highest peak on the islands, and the world's highest mountain in terms of elevation above its base. SLIDE 4 The volcanoes began their history above sea level during the late Tertiary, approximately ten million years ago. Moat of them became dormant either before or during the early Pleistocene; however, activity was renewed in the late Pleistocene. Even though only a few miles apart, each volcano in the Hawaiian Islands was built seemingly from an independent magma reservoir; each has an erosional history particular to it8 height and form; and each differs somewhat in age from the others. SLIDE 5 The volcanoes seem to have developed from the fissure in a northwest to southeasterly direction across the floor of the Pacific. The relative age of the islands is indicated by the extent to which they have been destroyed by erosion. SLIDE 6 Extending northwestward from Niihau are 26 reefs and shoals which mark the summits of submarine volcanoes, known as the Leeward Islands. These northweeternmost volcanic inountaina - 3 - have been eroded away until no more volcanic rock may be seen. The visible parts of Ocean and Midway Islands are forned entirely of oraanic limestone and calcareous sand, but at a depth of only a few hundred feet the limestone reefs rest on the truncated summits of great volcanic noun- tains. SLIDE 7 The islands of Rauai and Oahu were deeply eroded by streams and waves before a recurrence of volcanic activity buried much of their lowlands beneath layers of later lava flows. SLIDE 8 On Maul, the volcanic mountain cornpriaing the western part of the island has been deeply dissected by streams, with the formation of huge valleys such as Iao. SLIDE 9 Halsakala Volcano, forming the eastern part of Maul, also had great valleys cut into it by stream erosion before renewed volcanisn partially filled the work of the streams. SLIDE 10 Hawaii is the southernost and largest of the islands and also the youngest. Of the five volcanoes that built this largest of deep sea islands' (4,021 square miles), Kohala Volcano at the northern end of the island is the oldest.

SLIDE 11 Mauna Kea has not been active since the arrival of the Hawaiian people, but has erupted since its summit was covered by a small glacier during the Pleistocene Epoch about 15,000 years ago. SLIDE 12 Hualalai, on the western side of the island, has erupted once in historic time, during 1800-1801. SLIDE 13 The two southernmost volcanoes, Mauna Loa and Xilauea, are still quite active and almost completely untouched by the forces of erosion. SLIDE 14 The molten rock expelled by the valcanoes in reality is not a simple melt, but a complex solution of silicates and oxides. It appears always to contain volatiles, either dis- solved in it or simply enclosed in it as bubbles. Also, the molten rock often contains solid crystals of various miner- als, which have precipitated from the solution through a process of "fractional crystallization". This hot liquid is called magma. While the magma is confined under sufficient pressure, the gaseous constituents remain in solution; but, as the magma rises toward the surface and the overlying pressure is reduced, the gases escape, sometimes with explosive violence. When this magma is poured out onto the earth's surface it is referred to as lava. SLIDE 15 Lavaa vary greatly in composition. The composition affects the viscosity, thereby influencing the ease with which the gasea are liberated, and as a consequence determines the type of eruption, the rate of flow and other characteristics. When considering only the chemical elements in a solid state, the substances present are usually expressed as oxides of the various elements which the lava contains, The most abundant oxide in lavas is silica. In general, as the per- centage of silica increases so does that of the alkalies, and as it decreases there is an increase in the percenta~e of iron, magnesia and lime. The majority of Hawaiian lavas are nezr the silica-poor end of the scale and are relatively rich in iron, lime and magnesia.. SLIDE 16 The most coamon lava of all the Hawaiian volcanoes is the type known as olivine basalt. Its nost abundant constituent is a light-colored variety of plagloclase feldspar called labradorite. It generally comprises nearly half of the crystallized rock. SLIDE 17 The olivine basalt grades into rocks known as andesite, richer in silica and alkalies than the basalts and generally lighter in color. Andesite is not present at Kilauea and Mauna Loa, but is abundant in Nauna Kea and Haleakala on the island of Maui,

SLIDE 18 There are two principal types of lava flows produced by Hawaiian volcanoes, Pahoehoe flows occur when lava con- taining much entrapped gas spreads out in thin sheets. The surface of pahoehoe lava Is smooth and billowy and frequently molded into coiled, rope-like masses. SLIDE 19 Such billowy surfaces commonly develop in basaltic lava, on which a skin-like surface coivers the liquid lava below, and as the flow contlnuee to move' the smooth skin is wrinkled into ropey surfaces which are preserved on the perimeter of the pahoehoe flow when the mass finally solidifies.

SLIDE 20 The skin which develops on the cooling lava may further solidify forming a crust. SLIDE 21 This crust may eventually develop a more or less contin- uous roof, and the lava stream commences to flow within a tube of its own making. At the end of an eruption, most of the inolten lava may drain out of the tube leaving an open tunnel commonly as much as ten to twenty feet in diameter with an arched roof and a nearly flat floor. The floor is the final solidified surface of the lava stream which flowed through the tube. Such features are common in many pahoehoe lava flows and are referred to as lava tubes.

SLIDE 22 Aa lava flows, on the other hand, typically display a jag- ged or more blocky surface, as illustrated by this flow along the northeast rift zone of Mauna Loa; the summit of Mauna Kea towers in the background. The lava is generally void of gases and the vesicles, or bubbles created by the trapped volatiles contained within the magma, are replaced with air. The loss of these volatiles is responsible for the more rapid cooling and greater viscosity of this type of lava. SLIDE 23 The fresh flows of aa lava extending downslope appear black. The fresh pahoehoe flow8 may a180 appear black, but when -7- light is reflected fron them they appear silvery gray from a dist~nce,Older lavas are dark gray and still older ones reddish-brown, The reddish-brown color is a result of the advanced stage of oxidation of the iron contained in the lava. SLIDE 24 Despite their differences in physical appearance and nature of flow, chenical analyses of solidified fragments of the two types of lava from the same flow show them to be essentially identical in chemical conposition which suggests that rivers of pahoehoe may pour from volcanic vents or fissures, but as it flows downslope it loses its volatiles and consequently increases its viscosity and the lava eventu- .ally changes to aa. An aa lava flow from the 1950 eruption of Mauna Loa is shown here crossing highway 11 along the volcano's southwest flank, SLIDE 25 Where aa lava flows into the sea the contact of the hot lava with sea water causes steam explosions that throw up droplets and fragments of the hot lava, The droplets of still molten lava are quickly solidified to a black or dark brown glass. SLIDE 26 The debris from the explosions accumulates to form small hills at the edge of the water. These hills are attacked by ocean waves and soon eroded away, The sand-size fragments, moved along the shore by waves and currents, accu- mulate at favorable places to form beaches of black glass sand, such as the beach at Kalapana on the southeast shore of the island of Hawaii. SLIDE 27 The mobility of the molten lava depends on its composition and temperature, whereas, the speed of a lava flow depends on its viscosity as well as the degree of slope on which it is flowing. The difference between aa and pahoehoe lava may be summarized as a result of the state of the enclosed gases at the time the lavas solidified.

SLIDE 28 Hawaiian volcanoes are characterized by the eruption of these fluid basaltic lavas which are commonly expelled through fissures around the sides of the volcano as "quiet" flank eruptions. The reason why the Hawaiian volcanoes erupt so quietly as compared with eruptions on or adjacent to the continents is due to the great fluidity of the lavas and their corresponding low gas content. The three factors which determine the viscosity of any lava are: its chemical composition, its temperature and the amount of gas that It contains. Generally, the lower the silica content of the lava the less viscous it is, and likewise, the higher the temperature and gas content the lower the viscosity. If the lava Is highly viscous, the gas enclosed in it has difficulty escaping and consequently builds up a high pressure before it is able to force its way out through the vent. When it finally escapes, it does so with explosive violence. On the other hand, if the lava is less viscous, the contained Bases are able to escape easily without explosion. The relatively low silica content of the olivine -9- basalts combined with high temperatures add further cause to the great fluidity and consequent quiet eruptions of Hawaiian lavas. SLIDE 29 One evidence of this high degree of fluidity is the for- mztion of tree nolds and casts. When fluid pahoehoe lava surrounds a tree, the lava is chilled against the tree trunk end hardens. The tree then burns and the charcoal and other debris are eventually washed away by rain and blown out by wind, leaving a cylindrical hole in the lava where the tree once was located. If the lava is sufficiently fluid, after the eruption has ceased the lower portion of the flow may drain away, lowering the flow surface and leaving the tree molds projecting as high as ten feet above the ground level. These projecting columns are known as lava trees. SLIDE 30 Although explosive activity is relatively rare due to the fluidity of the lavas, several explosions have occurred on Hawaii during historic tines. Perhaps the most famous was the explosion of Kilauea in 1790. This explosion consisted of fragments torn from older related volcanic rocks in the walls of the conduit, called ejecta, and violently ex- panding magmatic gases. The ejecta from this explosion overlie the ash deposits which were laid down during a preceding phase of the eruption just prior to the explosion. These ashea combined with water vapor in the steam cloud and essentially rained mud. This mud has now compacted - 10 - into clay and still preserves the footprints made by Hawaiian warriors passing by Kilauea just before they were annihilated by the toxic gases blown out during the explosion. SLIDE 31 The volcanoes of Hawaii fall into two categories... broad, shield-shaped domes, such as Mauna Iki, consisting chiefly of thin-bedded lava flows dipping 3' to 20' away from their respective summit vents and rift zones; and steep domes studded with cinder cones. Mauna Loa, Kilauea and Kohala illustrate the flat, shield type of dome; whereas, Mauna Kea and Hualalai illustrate the type characteristic of the steep domes. SLIDE 32 Hauna Kea owes its steepness to a cap of alternating lavas and associated pyroclastics. This steep dome, nevertheless, is underlain by a typical flat, shield-shaped dome composed of older lavas. SLIDE 33 Having considered the development and some of the general features of the Hawaiian volcanoes, let us now examine the fluctuating forces of erosion which perpetually work to create and destroy the many faces of Madam Pele. SLIDE 34 Although the Hawaiian Islands are at the northern margin of the tropics, they have a subtropical climate because of the influence of cool water from the Bering Sea. This relative coolness is, in part, the reason for the poor development of coral reefs along the ialand shelves. SLIDE 35 The Islands lie in a belt of northeast trade winds which persist throughout the year. The mean direction of these winds is not consistent but shifts over a number of years, progressively east and then north again. This change in wind direction is important because shifts in the precipitation affect the erosive power of the streams. Southerly winds which blow for only a few days at a time occur occasionally during the winter months. Both the trade and southerly winds bring rain to the islands; however, the heavy storas usually come from the south. SLID3 36 During the week of December 9, 1969, towering waves from one of these southerly or kona winds washed away this entire broad, white sand beach at Polihale, where West Kauai's coastal plain meets the majestic Napali cliffs. SLIDE 37 However, the northeastern sides of the ielands are usually the wettest because the prevailing trade winds are from that direction. These winds blow across miles of ocean before reaching the islands and consequently arrive laden with mois- ture. SLIDE 38 The maximum precipitation occurs between altitudes of 2000 and 6000 feet depending on the shape of the island. Above 6000 feet the precipitation decreases, making the high peaks semiarid. SLIDE 39 It is on these peaks that the silveraword plant has been able - 12 - to find a suitable ecologic niche. This plant has efficient sun-reflecting leaves which are covered with silvery hair- like projections to protect it from evaporation on the sun- drenched, cinder-covered summits. SLIDS 40 As the trade winds descend the southwesterly slopes, they become warn, drying winds, causing arid and semiarid climates on the leeward sides of the islands. SLIDE 41 On the island of Hawaii, where the mountains are sufficiently high to pierce the layer of trade winds, eddy currents result in prevailing southwest winds on the leeward side so that the climate along the western coast is fairly wet and quite s11it- able for the cultivation of coffee and makadamia nuts. SLIDE 42 These eddies are also responsible for the deposition of large areas of wind-drifted, volcanic sand. This dune-like deposit is located at an elevation above 9,000 feet along the northeast flank of Mauna Loa. SLIDE 43 Mt. Yaialeale, on the island of Kauai, is hidden by dense clouds an average of 360 days of the year. The summit often receives over 600 inches of rain annually and is considered to be the wettest spot on the earth's surface. SLIDE 44 On the contrary, the islands of Kahoolawe and Lanai are relatively low and sheltered from the trade winds by other islands and consequently are very dry. Following overgrazing and deforestation, the wind has eroded large quantities of soil from these islands and during windy seasons dust clouds commonly extend many miles over the ocean. SLIDE 45 It is apparent that rainfall plays a vital role in controlling the various climatic conditions of the islands; likewise, it is vital in determining atream flow and coneequently the amount of erosion. SLIDE 46 The mount of erosion varies significantly on the different slopes of the same volcano. The windward slopes of the larger islands may be dissected by deep canyons because of the high rainfall. .. SLIDE 47 whereas, the leeward sides may be eroded by relatively small gulches. SLIDE 48

Difference8 in the age of the lavas on two sides of a mountain often give rise to stages of erosion contrary to what nornally would be expected. For example, on the Waianae Fiange along the southwest coast of Oahu, the leeward slope is older, therefore, much more eroded than the windward side. SLIDE 49 Furthermore, the rate of erosion on a volcano may be hindered by the development of another volcano to the windward, as happened when the Koolau dome cut off the trade winds from the 'daianae iiange to the southwest. SLIDE 50 The rate of erosion Is also affected by the great permeability of the coral rock and olivine basalt. Likewise, this factor plays an inportant role in the geoaorphology of the islands. SLIDE 51 For exanple, even though rainfall is high in the vicinity of Ifilauea, stream channels are unable to develop on most of the volcano due to the high surface porosity. SLIDE 52 The porosity and fractured condition of the rocks enable even slightly viscous pahoehoe to drain into the lavas of older flows. At an elevation over 10,000 feet along Ivlauna ~oa's northeast rift zone, this pahoehoe flow had developed a crust and terminated its downward advance when the molten liquid beneath the crust found a new route in the fractured lavas underlying it. Streams develop slowly over the surface of an extinct volcano as a result of this high permeability. Once established, however, they erode quite rapidly because of the steep slopes and the fractured condition of the rocks, which is due to contraction of the cooling lava. Stream development may be enhanced by the production of lateritic soils which reduce the porosity of the slopes. SLIDE 53 Cheaical weathering in ~awail'ssubtropical climate is the chief agent in the formation of soil, because frost and ice do not occur, except'on Mauna Loa and Mauna Kea. Mechanical disintegration resulting from temperature fluctuations is slight, since diurnal changes in temperature are small. SLIDE 54 Weathering takes place more rapidly in vesicular Java and in the blocky aa flows than in the more massive beds. In general, weathering penetrates deeper along fractures and dikes than in the adjacent flow socks. SLIDZ 55 The depth of weathering varies from place to place with clinate, steepness of slope, rate of soil erosion and age of the lava flows. Soil-covered, friable lavas followed up the slope of an adjacent mountain, where the ~ainfallis less and the temperature lower, becoze firm and nearly free of soil. Likewise, a soil'a thickness decreases when traced into the serniarld and arid clinatea of the leeward coasts. SLIDE 56 Nevertheless, under favorable condf tions , soil devel~pnent proceeds quite rapidly, forming thick, red later1t ic soils whlch are responsible for the ialanda ' luah vegetation. SLID2 57

It Is apparent from this brief discussion of soils, that soil and stream development on the ielands of the Hawalfan chain depend upon 8iaZlar factors, mainly cllnute and ra2nfall. The typical stream drainage pattern which develops down the flanks af extinct volcanoes IBdescribed as radial drainase. SLIDZ 58 TBia steep radial drainage, developed on alternating layers of weak and strong, vertically jointed rocks whlch dip seaward, together with. the tlnusucslly high rainfall characterZstic of 2000 to 6000 foot elevations, have produced a dLstlnctive , 1. , ' type of valley beat described as amphitheatre-headed. Most of the larses islanda, except those covered with relatively recent lava flows, are dlasected by valleys of this type. Fol- - 16 - lowing are six factors concerned in the development of anphi- theatre-headed valleys. SLID3 59 The original slope of the land surface seems to be the most fundaaental influence contriauting to the formation of these valleys. Streams that originally flowed on slopes of about 3' or less have not developed amphitheatre-headed canyons; whereas, those that flowed over steeper slopes have, such as Xalalau Valley along Kauai's Napali coast. SLIDE 60 Less resistant, blocky aa beds are undercdt beneath the resistant layers of dense basalt and form waterfalls as the canyons are cut headward. Such falls increase in height as they follow the dip upstream and tend to combine into one high fall, for example, Moaula Falls near the head of Halawa Stream on East Nolokai. Most streams, like Halawa, have a "fall point", above which the stream actively erodes its canyon into the bedrock and below which the stream cuts laterally. SLIDE 61 The streams, flowing more or less radially from the center of the dome, are spaced relatively far apart in the region of low altitude and low rainfall. With increasing altitude 2nd the consequent increase in rainfall, streams increase in nunber and stream capture or piracy occurs. Thus, as the main stream captures smaller streams in Its headward advance, the stream enlarges into an amphitheatre near its source. SLID3 62 Furthermore, ground water sapping by springe also widens the sxphithestres. Thfs widenin? is a result of water percolating throush a permeable ash or tuff bed and flowlng to the sarface along s bodding plane, which is exposed along the valley wall or streaa channel. Sapping occuss when the escaping sround water erodes the aquifer so that the overlyin6 rock is under- mined. Eventually, the rock above the erodins aquifer fails and landslidins takes place. Undslidfng is an active process on the islands; however, the acars are overlooked because they become covered ao quickly with vegetation.

SLIDE 63 Captured tributaries entering the main stream form plunge pools around the amphitheatre wall. The narrow rid~esbetween the plunge pools are undercut, usually along a layer of ash or cinder weakened by saturation, and collapse under thcf r own weight, SLIDZ 64 Olivine basalt, characterlstfc of Hawaiian volcanoes, fs a competent rock capable of standing as vertical or neerly vertical cliffs. The vertical jointina common in basalt8 is also a contributing factor to its ability to atand as hish I cliffs, If the rocks were weak, the aheer amphitheatre walla ~ouldnot develop at the head of the valleys,

SLIDE 65 Tfie dip of the beda 18 probably important, but on the islands where the atsata rarely dip steeply, the role played by this factor ia not easily determined. Perhaps steeply dipping beda would not form the sheer walls necessary for amphitheatre development, SLIDE 66 Having considered the developinent of streain drainage f eatrlres and having examined the affects of wind and streain erosion, let us now consider perhaps the greatest erosive force of all.. . the seal SLIDE 67 Marine erosion la most effective on the northeast or windward coasts where towering cliffs preserve the affects of the sea's awesome power. The great sea cliffs, 2700 feet high forming the scenic Xapali coast on the island of Kauai, are a striking example of these windward cliffs. The cliffs were formed as the island submerged, the interstream divides composed of weak lavas being eroded far back into the volcanic rocks of the shield-shaped dome comprising the island. SLIDE 68 The Napali coast Is partially fringed by low, emergent coral reefs. These reefs, along with scattered calcareous white sand beaches, such as Haena on Kailiu Point at the eastern extent of the sea cliff, suggest the presence of a partially submerged wave-cut bench at a depth of approximately 25 feet. This bench represents a eustatic shoreline carved during one of the advances of continental Pleistocene glaciation. Eustatic changes in aea level were changes produced entirely by an increase or decrease in the amount of water in the oceans. Such fluctuations were world-wide and were caused by the varying amount of water locked up in the Pleistocene glaciers. SLIDE 69 Despite the apparent depositional featurea along .the coast and the presence of a wave-cut bench, the cliffs are still undergoing the attack of marine erosion. For example, such beaches as this one located near the nmth of Kalalau Valley, are only temporary. SLIaZ 70

During the winter aonths this beach and others like it are

washed to sea, once again leaving the towering cliffs exposed to wsve erosion. sLrns 71 Ancient lava tube8 burled beneath thousands of feet of younger

lavaa occasionally are uncovered by the waves. Marine abraeion

carve8 and expands these tubes into cave8 whlch often pene- trate hundreds of yards back into the cllffe. SLID2 72 As was the case with the amphitheatre-headed stream valleys,

sea cliffs along the lalands' windward coasts stand as a result of the competency of the vertically jointed volcanic rocks. SLIDE 73 The vertical joint8 are responsible, to a large degree, for ephezeral the developnent of the-strean courses whlch run down the steep slopes of the Napali cliffs.

SLIDE 74 These joints often intersect, in which case subaesial erosion

differentially weathers along these planes of weakness at a

greater rate than it is capable of eroding the massive rock between the joints, Thia differential weathering results in the formation of pinnacles situated at varioua points along the coaat. SLIDZ 75 Likewise, isolated steep ridges develop as a result of the epheneral coalascing on the upper slopes of-streams. This is due to the secondary radial drainage pattern which develops along convex portions of the cliff. SLID3 76 Along, the windward coast of West Maui, the 500 foot high sea cliffs generally plunge into deep water. Like the Napali cliffs, they too lie in the path of the prevailing trade winds; however, high waves break on these cliffs throughout most of the year because of the abaence of protecting coral reefs. SLIDZ 77 The nearly vertical cliffs are highest where they receive the full force of the wind-driven waves and become lower along those parts of the coast. which are protected... an observation which supports their marine origin. SLIDE 78 Due to the severe storms coming from the south and southwest during the winter months, the leewa~dcoasts, which are not protected by sheets of recent lava flows, also develop high sea cliffs, such as the ones near Kaapahu Bay along the southern coast of East Maui. SLIDE 79 Along the southeastern coast of the island of Hawaii, ten to fifty foot cliffs have developed in relatively recent lava flows. These cliffs, geologically, are very young and are undergoing rapid marine erosion as is demonstrated by the presence of numerous wave-cut archea and bridges.. SLIDE 80 The bridges are caused by waves eroding away tke loose parts of various aa flows, leaving the more maaslve lava to form the bridge. SLIDIS 81 The arches are formed in a similar way; however, their de- velorment is facilitated by the vertical jointing of the olivine basalts. As the waves erode back into the cliff alon~ these planes of weakness, the swirling action of the wavea ultimately erode8 circular depressions at the base of the cliff. An arch or a bridge forms when the divide between two adjacent depresshons f s worn through and continues to enlarge due to marine absaaion,

SLIDE 82 On the other hand, the leeward coast of the island of IuIolokai 1s protected f~omthe erosive force of the sea by fr2nsing coral reef8 which are Xn turn protected from the aav&ge attack of the southerly, kona otbmns by the Island of Unaf to the south,

SLIDZ 83 The coral reefa protect nuch of the shore from the attack of heavy wavea because the surf breaka at the outer edge of the reefs , SLIDE 84

However, the presence of these fringing reefs somewhat com- plicates marine erosion on other coaata which are unsheltered by leeward islands, because during etorms the large wavea will pass completely over the outer ridge and break on the ehore. Likewise, the intensity of wave erosion varies with the width of the reefs. SLIDE 85 These limestone, coral reefs are the source of the islands' calcareous, white sand beaches. The scarcity of unbroken shells on these beaches further illustrates the affects of marine abrasion. PART I1 SLIDE 86 During the preceding discussion we have considered the history of the Hawaiian Islands as well as the nature of their development and have examined some of the basic geomorphic concepts concerning erosional features. Now let us exemine some of the particular geomorphic features characteristic of the major islands as well as the individual islands' ~ross land forms. SLIDE 87 The island of Hawaii has been built by lavas poured from five volcanoes, each with independent rift zones and individual geologic history. Their areas* and the principal geomorphic features are illustrated by this map. Kohala Dome comprising the extreme northern part of the island is the oldest, its southern slope having been buried beneath younger Mauna Kea lavae. SLIDE 88 'then the amount of lava extruded from the Kohala Volcano exceeded the amount of collapse, the caldera and grabens were partially or entirely obliterated. High lava fountains characterized most of the eruptions and large cinder cones were formed, such as this one situated along Kohala's west - 23 - flank. Furthermore, the volcano developed into a bulbous lava dome. Ash beds increased in number and thickness and the pro- file of the done steepened. Hualalai and Mauna Kea are also in this stage of development. SLIDE 89 Mauna Loa and Kilauea represent a younger stage of development, one in which the volcano collapses over the vent to forn a caldera on the sumnit and shallow grabens along the rift zones. SLIDE 90 Mauna Loa.is the world's largest active volcano and probably the largest single mountain of any sort on earth. It rises 13,680 feet above sea level and approximately 30,000 feet above its base on the ocean floor. In form, Mauna Loa is a very broad, flat dome, the slopes of which at no point are steeper than about 12O, and near the top the slope is as little as 4'. Similar slopes extend outward beneath the water all the way to the sea floor. SLIDE 91 On the summit of P.launa Loa is an ovzl depression three ailes long, one and a half miles wide and as much as 600 feet deep called 14okuaweowe0, a caldera formed by the collapse of the sunmit a8 great quantities of magma subsided from the reservoir beneath the volcano, thereby withdrawing the summit's support. SLIDE 92 &fauna Loa is located on a well-defined rift zone which trends in a northeast to southwest direction. This rift zone is approximately at right angles to the main fissure over which the Hawaiian Archipelago is located; the intersection of the - 24 -

two zones may be responsible for the location of the volcanic vent. The rift zone on Icauna Loa is marked at the surface by

, many open fissures and cinder and spatter cones built during flank eruptions. SLIDE 93 Trench-shaped depressions or grabens, formed by blocks sinking between roughly parallel faults, are common in the rift zone

of Mauna Loa. The collapse i8 a volcanic process similar to that which forms the calderas, except that it results in longitudinal instead of circular depressions. SLIDE 94 Repeated outflows of lava in the rift zones tend to compensate

for the collapse; therefore, the depth of the grabens is only a fraction of the total collapse that has taken place. SLIDE 95 The cinder and spatter cones which develop along Mauna Loa's southwest and northeast flanks are a result of the accumula-

tion of spatter and fragments of lava thrown into the air from the lava fountains which charabterize Hawaiian flank eruptions. SLIDZ 96 Some of the gobs of liquid lava solidify in the air and pile up into loosely cemented cinder cones upon striking the ground. SLIDE 97 !dhen a lava column froths or the magma is very fluid, spatter accumulates around Isolated vents as mounds; these mounds are called spatter cones. - 25 - SLIDE 98 From the vicinity of Kilauea caldera, the slopes of Mauna Loa show many variations in color, depending on the age and surface characteristics of the different flows. SLID3 99 Throughout the past century Mauna Loa has been one of the most active volcanoes on earth. It has erupted on an average of once every 3.7 years and its eruptions during that period have extruded a total of more than three and a half billion cubic yards of lava. Mauna Loa last erupted in 1950 with the present quiet period of twenty years being the longest in its history. SLIDE 100 Kilauea Volcano is located on the southeast slope of Mauna Loa about 10,000 feet below its summit. It appears to be a crater on the side of the higher mountain, although in reality it is a separate lava dome approximately fifty miles long and fourteen miles wide. Kilauea has been built largely by eruptions from two rift zones, extending eastward and southwestward from the summit caldera. The Chain of Craters Road passes close to several of the pit craters along the east rift zone. SLIDE 101 These pit craters are formed by collapse caused by removal of support. Some of the smaller ones may be formed by draining of large lava tubes beneath the surface, with resulting collapse of the overlying rock material into the tube. The larger ones, such as Makaopuhi Crater at the end of Chain of Craters Road, probably form above pluglike bodies of magma that work their way upward along the rift zone. Partial withdrawal of - 26 - the magma causes the unsupported mass of rock above to collapse foraing a circular depression. SLIDE 102 The summit caldera of Kilauea is an oval-shaped depression two and a half miles long and two miles wide, the lava- covered floor of which is about 400 feet below the vertical cliffs. On the floor of the caldera, near the southwestern edge, is the depression Haleaaumau, a collapsed crater about 3200 feet wide. Halemaumau is the focus of Kilauea's eruptive activity and the traditional home of Xadam Pele. SLIDE 103 Typical eruptions of Kilauea consist of lava flows forming lava lakes in Halemaumau or of short-lived lava flows within the crater and flank flows from fissures along the rift zones on which Kilauea is situated. SLIDE 104 On November 14, 1959, a crack opened on the southwest wall of Xilauea Iki, a pit crater iainediately adjacent to the eastern edge of Kilauea caldera. A line of lava fountains 1200 feet long spurted up along the crack and cascades of lava poured into the crater, burying the old flow of 1868 lava. SLIDE 105 By November 21 only one fountain remained, and the vent of this fountain was buried by a pool of lava 300 feet deep. That evening the fountain suddenly died. However, following four days of no activity, sixteen brief eruptive phases occurred. At the end of each of these phases, liquid lava - 27 - drained froa the pool back into this vent. SLID3 105 The lava fountain reached a rnaxilnun measured height of 1900 feet, the greatest ever recorded in Havaii. This resulted from an unusual abundance of gas in relation to the amount of liquid lava. SLIDE 107 Cinders and spatter from the fountain piled up on the crater ria, building a conical hill 150 feet high. SLIDE 108 Pumice forned a blanket as much as five feet thick a half a mile from the vent, viewed here along Devastation Trail. SLIDE 139 When the eruption ended on December 21, the pool of new lava in the crater was 380 feet deep. Seven months after the eruption had terminated, the crust of the Kilauea Iki lava lake was found to be about nineteen and a half feet thick; this increased to 100 feet by 1967. SLIDE 1 10 Along with these features directly associated with the recent eruptions of Kilauea and Mauna Loa, fault scarps, likewise, are geomorphic features associated with the activity of these volcanoes. It is believed that the eruptions under the sea were commonly expl~siveand that the submarine foundation of the volcanoes contains much more pyroclastic debris than the parts above sea level.

SLIDE 11 1 These relatively unstable materials in the base of the island nzy account for the great number of faults dipping seaward along the coasts. For example, Puu Kapukapu, a thrusted fault block, forms the coast south of Halina Pali along the southwest flank of Kilaueu. This horst reaches a maximum height of 1,050 feet above the Pacific.

SLIDZ 112 To the north of Kilauea and Mauna Loa lies the Waiamea Plain, a flat land 2,500 to 3,000 feet above sea level between Mauna Kea and the Xohala Hountains. It has an area of twenty-five square miles and is covered with an ashy soil which is underlain with lavas from Wauna Kea. This plain developed as a result of theue lavas flowing against the older dome of Kohala.

SLIDE 1 13 Maui, the second largest island of the Hawaiian group and next to the youngest in age, is comprised of two volcanoes.

The East Maui volcano is known as Haleakala or "~ouseof the sun". The West Maul volcano is dissected into several high peaks and is generally referred to as the West Maul Mountains.

SLIDE 1 14 West Maui is deeply eroded by streams, many of which rise in deep amphitheatre-headed canyons. These canyons radiate from the summit like the spokes of a wheel. The most famous is Iao Valley, towered over by the Iao Needle. This abnormally broad, circular amphitheatre, located to the west of the city of 'dailuku, was caused largely by the stream draining the former summit caldera of the West Maul volcano.

SLIDE 1 15 Although rift zones are known, this asymmetrical dome ap- - 29 - proaches the "central type" of volcano, in contrast to the II fissure type", because igneous dikes radiate in all direc- tions from the ancient caldera and alnost all the lava beds are steep, and it appears that many of the lavas were extruded fro~na central vent.

SLIDE 1 16 Flow slope plains are extensive on West Maul and forn valuable agricultural land. Host of the land planted in pineapples and susar cane is of this type. They are sloping plains with grades rangine; from 200 to 400 feet per mile. Their surfaces conform very claaely to the surfaces of the lava flows underlying them. Most of these plains become plateaus a short dis- tance inland.

SLIDE 1 17 Wind erosion of steep ridges, especially since deforestation, has left numerous scars in exposed headlands. Continued ef- fects of wind and water erosion have produced a bad-land topography in the deeply weathered rocks along the seacoast of the northern slopes.

SLID2 1 18 Unusually regular benches have been cut by the wind in this area, as is illustrated in this slide by the wind-cut bench situated on the left horizon.

SLIDE 1 19 Haleakala is the large volcanic mountain that forms the eastern part of the island of Maui. It started its growth aa a typical shield volcano like Kilauea and Mauna Loa. Thousands of thin flows of olivine basalt and closely related lavas followed each other in rapid succeaslon, until the - 30 - shield had been built from the ocean floor to an altitude of about 11,000 feet above the present sea level. SLIDE 120 At that stage the frequency of eruptions decreased, weathering produced soil lagers on the surface of some flows before suc- ceeding flows were able to bury them, and slow changes in the magma body beneath the volcano produced new rock types which consisted largely of andesites. Toward the end of the eruption of these andesites, volcanic activity decreased greatly in intensity, although it probably did not cease altogether. Erosion was able to keep pace with the accumulation of new lavas and streams cut great canyons into the slopes. Some of these were several thousand feet deep. SLIDE 121 Two of these streams, forming the Koolau and Kaupo canyons, cut far back into the summit of the mountain and their heads. coabined to form one great central depression divided only by a low narrow ridge separatiw their drainage areas. This depression forms the present "crater" of Haleakala, which is thus erosional, not volcanic, in origin. SLIDE 122 At a still later time volcanism again increased in intensity and a series of'lavas and cinder cones were erupted. The lavas were erupted principally from a line of fissures, forming the southwest and northeast rift zones of the volcano.

SLIDE 123 The original floors of the eroded valleys have been deeply buried beneath the lavas and cinder cones that form the present floor of the crater. SLIDE 124 Koolau gap, shown here along the northern edge of Haleakala crater, is all that remains of a former deep stream-carved valley now filled by younger lavas.

SLI3E 125 Haleakala is the only volcano of the Ilawaiian Islands, with the exception of the island of Hawaii, that has erupted during the last few hundred years. About 1790 lava poured forth from two vents on the southwest rift and formed a flow that went into the sea. La Perouse Bay is a reentrant between two pen- insulas built by this relatively recent flow. SLIDE 126 Deposition and erosion along the west coast of East Maul are nearly in equilibrium as a result of being on the leeward side of Haleakala and being protected from kona storms by the island of Kahoolawe to the south. SLIDE 127 Another factor in maintaining the beaches along this coast- line was the introduction of large trees which anchored the beach dunes by vegetation. The trees deflect the, wind upward and stop the drifting of sand inland. SLIDE 128 Generally, however, the coastlines of Maui are unsheltered and subjected to wave attack. The less resistant beds of late lava flows, when exposed to marine abrasion, give rise to spectacular caves, natural bridges and stacks. A stack is an isolated, steep-sided rock mass just off the end of a promontory which has been Isolated from the land by marine erosion, concentrated just behind the end of the headland, as illustrated by this stack located in Pailoa Bay along the Hana coast. SLIDE 129 The remaining geomorphic feature of particular interest is the Isthmus connecting East and West Maui. This isthmus is composed chiefly of lava flows from Haleakala Volcano. It was built by these flows ponding against the older volcano of West Naui. The lava beds dip about 12' on the summit of Haleakala but are practically horizontal on the Isthmus. ivluch of the isthmus is covered with alluvium, deposited mainly by streams from West Maui. The streams of East and West Kaui are torrential and flow over steep gradients. Irken they reach the flat bottom land their velocity decreases and they drop most of their sediments. The Isthmus is the center of Maul's population and its eastern edge supports the world's largest sugar plantation. SLIDE 130 The island of Mol~kai,lyins to the northwest of Maul across the Pailolo Channel, is comprised of three volcanoes. The western one, known as West 3loloka1, is 1,380 feet high and about twelve miles across. The eastern one is called East Xolokai Mountain. This volcanic dome is 4,970 feet high, eight miles wide from north to south and 27 miles long. A' smaller and much later volcano forms the Kalaupapa Peninsula on the north coast of the eastern volcano. The Hoolelua Plain or Isthmus of Molokai is composed of lava flows which were extruded from the East Molokai Volcano. The plain de- - 33 - veloped as a result of these flows banking against the older Vest 24olokai Dome. SLIDE 131 The lava beds dip 6' to 10' on the crest of Xast ?:olokai in

the back~roundand only lo to 3' on the Hoolehua Plain. Most of the plain is covered with ten to thirty feet of red, lateritic soil, which is quite suitable for the cultivation of pineapple. SLIDE 132 Overgrazing, since white men introduced livestock, and the

cultivation of this land have accelerated erosion, and large flats of red soil washed from the plain are now forming along the south shore. SLIDE 133 l:ost of West Xolokai is, likewise, covered with lateritic soil ten to fifty feet thick, indicating long extinction. This volcano has a flatter dome than most of the others in the Hawaiian group and consists almost entirely of thin- bedded aa and pahoehoe basalt flows. SLIDE 134 The East Molokai Dome is cut into great amphitheatre-headed valleys on the windward side of the island and is dissected ephemeral by numerous- streams along its leeward slope, a part of which is illustrated here. SLIDE 135 At the foot of the great windward cliff of the East Molokai Mountain, during the late Pleistocene, a small volcano was formed and flows from it have built a low peninsula about - 34 - four square miles in area and 405 feet high. A crater 400 feet deep indents the summit of the dome and can be viewed in this slide in the upper left corner. SLIDE 136 The volcano is known as Kalaupapa and, due to its isolation from the main part of the island, used to be the location of a leper settlement. The submarine portion of the Kalaupapa Volcano is huge and may well represent the young stage of a great new dome. SLIDE 137 The island of Oahu is made up of the Waianae Range, 4,025 feet high and 22 miles long, and the Koolau Range, 3,105 feet high and 37 miles long, connected by the Schofield Plateau which lies between the mountains. Both ranges are deeply eroded basaltic volcanoes of which the Waianae Volcano became extinct first. SLIDE 138 The Waianae Range forms the western part of Oahu. The western tip of the range and of the island is Kaena Point. On this wind-swept point the wind is constantly drifting grains of sand and small fragments of shells upward and out of the reach of normal waves. SLIDE 139 As a result, dunes twenty to thirty feet high develop; however, their spread and growth are retarded by windbreaks and the introduction of sand-dwelling plants which tend to hold the dunes stationary. SLIDE 140 The striking features of the Waianae Range are the great flat-floored valleys that indent its vestern slope, such as

Lualualei Valley shown here, 2nd the hi&, corrugated preci- pice that joins the heads of these vzlleys. The eastern slope is more gradual and ka dissected by relatively small, narrow valleys.

It is exceedingly unlikely that the &reat valleys on the west side of the range could have been carved out under present conditions of rainfall, the west side now being virtually a cactus desert. Consequently, it may be assumed that the maJor portion of valley development took place before the younger

Koolzu 9awe reached a suffScZent height to intercept the nolsture laden trade winds.

SLIDE 142

Stream erosion created the characteristic amphitheatre-headed valleys; but, due to the fluctuating energence and submer&ence of the ialand during the Pleistocene Xpoch, these valleys have been partially f illed with alluvium. SLIDE I43 Furthermore, due to the age of the valleys, the interstream divides of the amphitheatres have been ~ubstantfally eroded away by the ocean, leaving cliffs along the coast as nuch as two miles in length. The heada of these amphitheatre valleys appear now only aa reentrants along the coast. SLIDE 144

The lavaa of the Koolau Volcano were extruded in Tertiary time from three rift zones, Host of the lava was extruded froa the northweat rift zone as ia demonatrated by the extension of the island in that direction. The main streams of the Koolau Range also have cut deep amphitheatre-headed valleys into their slopes. SLIDE 145 During the erosion cycle, a large part of the windwar6 slope has been eroded away by these streams. As a matter of fact, erosion has been so extensive that it is doubtful if any part of the original surface of the Xoolau Dome remains, The great pali, or northeast cliff of the range,is the result of two processes, SLIDE 146 First, the streams of the amphitheatre-headed valleys eroded their canyons headward and a little beyond their interstream divides, and second, nost of the interstream divides were buried beneath deposits of alluvium which accompanied the deep submergence of the islands during the Pleistocene. The rid~esshown in this slide lie adjacent to the great reentrant of Haiku Valley west of Kaneohe and are remnants of the valley's old interstream divides now partially buried beneath hundreds of feet of alluvial sediments, SLIDE 147 Along most of the shore of the island of Oahu is a coastal plain, which reaches a maximum width of nearly six miles at Pearl Harbor. The plain is interrupted or very narrow at the ends of some of the mountain spurs and at the east and west tips of the island. It is this coastal plain that has made Oahu the commercial center of the Hawaiian Islands, because it has provided excellent harbors, supplied extensive areas - 37 - of valuable agricultural land and has made the developaent of a transportation network less costly. SLID3 148 The plain ranges in altitude from sea level to about eighty feet. The Coastal Plain itself is the product of several shifts in sea level and consists essentially of reef liine- stones and noncalcareous marine sediments. SLIDE 149 The branching lochs of Pearl Harbor are believed to have been formed by a group of dendritic valleys previously carved by subaerial erosion in horizontal rocks during an emergence of the island during Quaternary time. The harbor is a result of these dendritic stream valleys being submerged by the present stand of the sez. SLIDE 150 The island of Kauai, known as the Garden Island because of its lush vegetation, is formed by a single volcanic dome 5,170 feet high and 32 miles in diameter. The summit caldera of this basaltic dome and the adjacent Waialeale Plateau are covered by the great Alakai Swamp.

SLIDE 151 Since the plateau lies between the 2000 to 6000 foot elevation of maximum rainfall, the summit receives a daily accumulation of precipitation from the trade winds. As a result, the island has been deeply dissected by stream erosion, the majority of these streams having their origin in the Alakai Swamp. SLIDE 152

Along the northwestern edge of the plateau are the 2700 foot high Napali cliffs. The origin of these cliffs was previ~usly explained as a result of marine and stream erosion. SLIDE 153 It should be added, however, that the streams which carved the najor valleys originated in the Alakai Swamp; whereas, the ephemeral -streams which form the nearly vertical ridges are a result of local showers. SLIDE 154 ephemeral The energy of these -streams varies with the degree of slope, as is easily demonstrated by the accumulation of debris and weathered rock material at the base of this cliff. The runoff is highly abrasive as it runs down the steep walls; however, once the stream reaches the more gentle slopes near the bottom of the cliff, it loses energy and deposits its load. The accumulation of this weathered rock facilitates further accumulation since the runoff will rapidly soak into the loosely consolidated sediments. SLIDE 155 ephemeral Consequently, many of these -streams may never reach the sea in a water course; but, on the other hand, the water may percolate through the unconsolidated sediments along the surface of the more resistant, underlying basalt and reach the sea as spring discharge along lower portions of the cliff or may even be discharged below sea level. SLIDE 156 The stream valleys of Kauai are more extensive than the valleys of the other Islands. Hanalei Valley, bordering the meandering Hanalei River, is a wide plain for many miles, - 39 - becoming a narrow gorge near its source on the northeastern slope of ldaialeale. SLIDE 157 Furthermore, the Wailua River, the chief river of Kauai and the largest and only navigable river in the islands, is situated within the shore plain east of the Waialeale Plateau. The river is approximately fifty yards wide for the last two miles of its course to the sea, SLIDE 158 The shore plain is a series of plateaus built up by Pleistocene lava flows which were extruded from scattered vents located at various points along the summit's eastern slope. These Pleis- tocene flows are unconformable on the underlying Tertiary lavas . Consequently, where the unconf ormity has been exposed in stream valleys, waterfalls have developed as a result of the differences in the resistance of the flows, the younger Pleistocene flows having a greater degree of competency. SLIDE 159 Aside from the summit plateau and the shore plain, there are some ridges near the eastern shore which appear to be distinct from those aesociated with the summit plateau, since they lie between the plain and the sea. One of these is the Hoary Head Ridge, which standa along the southeastern coast of the island. The ridge is most likely the product of fissure eruptions along Waialeale's southeast flank which erupted after the main conduit of the summit was sealed. Such eruptions may likewise have been associated with rift zone activity or the volcanism which produced the ridge may have been independent from that which formed the WaialeaIe Plateau. If the latter was the case, the lavas comprising the ridge were probably extruded from an independent magma reservoir. Nevertheless, the lavas are Tertiary in age and are not associated with the renewed volcanic activity of the Pleistocene Epoch.

SLIDE 160 Waiaaea Canyon is situated to the southwest of Mount 'ulaialeale.,

Its origin is, in part, explained by faulting; that is, the position of sose of the river's tributaries have been determined by the orientation of faults.

SLI3E 161 Bowever, the major portion of the canyon owes its position to a displacement westward by lava flows which were extruded during the Pleistocene. These lavas, as previously mentioned, were more resistant than the older Tertiary lavas, and consequently, the Waiamea River altered its course through the less resistant volcanics at the edge of the Pleistocene flows. SLIDE 162 The canyon owes its large size and 2800 foot depth to the fa'ct that the river drained the major part of the summit caldera, where rainfall is even now in excess of 450 inches per year. SLIDE 163 Xauai's shores support a growing, narrow coral reef. The reef is absent altogether along the sides of cliffs where the depth is too great and is also absent adjacent to the mouths of streams where detrital sediments prohibit any coral colonies from developing. Sand brought downstream from the plateau and calcareous, marine-abraded coral are transported along the coast by currents, finally being deposited as'white sand beaches in bays and along other protected shore lines. SLID3 154 Where the more recent lava flows are exposed to wave attack, lava tubes directly beneath the surface often have an open end in the coastel rocks. If such is the case, waves force water through this tube and the sea water is expelled through a hole in the roof as a noisy, salt water fountain. The Spouting Horn, shown here, is such a fountain located along ~auai'ssouthern coast. Similar fountains occur on the other islands, the most famous of which is the Blow Hole on the island of Oahu. SLIDE 165 The Hawaiian Islands were occupied by people of the Polynesian race about 450 A.D, The Polynesians were daring voyageurs and made long exploratory journeys in their large, sea-worthy canoes. With their families, food, plants and animals, some migrated to the islands of Hawaii, SLIDE 166 A second wave of immigration, probably from Tahiti, arrived about the year 1100. For some reason these migrations ceased, and the people wlio had journeyed here were left in isolation for several hundred years. The first recorded contact by Zuropeans with the Hawaiian Islands waa In 1778 when they were visited by Captain James Cook. SLID3 167 The islands soon became an important shipping center as a result of their geographic location in the central Pacific. Today, in many places, concrete has replaced palm trees, and the island paradise is at the mercy of comaercial ex- ploitation. SLIDE 168 However, much of the enchantment and tropical beauty of the islands still remain. Furthermore, the islands provide a first hand illustration of the development of marine volcanoes as well as furthering our understanding of the geomorphic processes involved in altering their form,

SLIDE 169 The work of Xadam Pele continues, how long she will remain on the islands is uncertain. SLID3 170 However, one thing is certain.,. Madam Pele is illusive and

much of her story remains to be deciphered, while... SLIDE 171 much of it is forever lost in the forgotten records of time, BOOKS

Bullard, Fred bl., Volcanoes in History, in Theory, in Zruption, Austin: Vniversity of Texas Press, 1962.

Dana, James D., Characteristics of Volcanoes with Contributions of Facts and Principles from the Hawaiian Islands, New York : Dodd, Nead, and Company, 1891 .

Eardley, A. J., General Colle~eGeolo~y, New York: Harper and Row, Publishers, Inc., 1965.

Easterbrook, Don J., Principles of Geomorphology, New York: McGraw-Hill, Inc ., 1969.

Hinds, Norman E.A., The Relative Ages of the Hawaiian Landscapes, Volume 20, No. 6, Berkeley: university of California Press, May 1931.

Jaggar, Thomas A., My Experiments with Volcanoes, Honolulu: Advertiser Publishing Co., Ltd., 1956.

Jaggar, Thomas A., Origin and Development of Craters, The Geological Sooiety of America - Memoir 21, Baltimore: Waverly Press, Inc., 1947.

Leet, Don L., and Judson, Sheldon, Physical Geology, Englewood Cliffs: Prentice-Hall, Inc., 1965.