At This Site, the KT Ejecta Layer Is 2 to 3 Mm Thick

Home , Shocked quartz

5 At this site, the K-T ejecta layer is 2 to 3 mm thick. 4 It consists almost entirely of tiny spherules. 3 U -~ • .~~V-- VU~ ~ 2-3 mm thick The iridium concentration is -~~L~~~~"'~~ -~ - I 24.4 ppb. I I I 2 I I I I I I I I I I 1 I I I I I I I I I I 0cm ■ Spherule O Ni-rich spinel f} Clay ~ M udstone U

Spherules in the ejecta layer (Ph otos courtesy of Jan Smit, VU Universit y Amst erdam.) HHMI HOWARD HUGHES MEDICAL INSTITUTE 2

25 I I I I I I 20 I I I I The evidence at this site comes from I a core drilled into the rock across the I I road from an abandoned building 15 that used to be owned by the An -- 5 m thick tioch Church.

I The ejecta deposit here is about 5 I I I meters thick and contains spherules 5 I I I and i m pact '' b rec c i a," which is a de I I I I posit of broken-up rock. I 0 m Spherule 0 Breccia tfp_;j Clay ~ Mudstone ~

The K-T event deposit contains spherules

(Ph ot o courtesy of Bru ce Simonson, Oberlin College.) HHMI HOWARD HUGHES MEDICAL INSTITUTE 3

30 II II II II II II II H H

·•:· · · · ·...... ··a·· ... ·...... :t}. ... : •: :· ·:.. · ··0 · · · · :· . ':•(! ... ..• ·• ..• • :• • :• : • • • • - ♦ The ejecta layer at this site is about .• • • •. •. •• • • •. • . .• .• • • • ••.. 20 •• • • • • •• • • • • • • • • • • • • . • .• ~ -• .• • • • .• • ♦ • .....• • • •• . •• ' •. • . •• . • .• ..• • . •. • ..• • ' •. ••••••• ...... • . . • •. • • . • . ' .• .• . . • . . 12 cm thick, and it contains large • •• • • • • • • • • • • • • ••••• • •• • • • • • • • • • • • • • • ♦• • • •: .•. • .. .. •. • .• • .. • . . .• • .• • ..• : .• .• .• .. ••••. . .. • ♦• • • • • ••••• • • •• • • • • • •• • •• •• • • • • • •• • ••••••• • • • shocked quartz grains, iridium, Ni .•. •• .• ...... ••••• •• • ··• •a • ··•. • .• . •• .• ...... •••••••• . ·a...... ·.. 21•t·····...... ·-- 12 cm thick .:· ..(;? ....., ...... v. ·. rich spinels, and tektites. • • • ••• • • ·n·: .. - ~:-~. :a:~ =~-,~ ~-·. :·:. . • • • .~• • • ..• •• • • • • • .. -::,• c.-;>•· ~·- ·::• :. .. • • • • • • 10 • ••• • • • • • • • • • ♦---• •

11 II II 11 II II II II II 11 II 0 cm II Tektite c:::) Shocked quartz D

Ni-rich spine! ~

Limestone ~ 1 1 ~

. . . - ~ .. Sandstone : :::::·:. • • • •

Pictures of tektites found at this site

(Photos courtesy of Jan Smit, VU University Amsterdam.) HHMI HOWARD HUGHES MEDICAL INSTITUTE 4

2.5 I I I At this site, you will find Cretaceous I I I ''mudstone'' just below the K-T 2 I I I I boundary. Scientists believe the mudstone, which is uniformly dark gray, was deposited in water 50-100 1.5 meters deep. At this depth, the ~ 1 m thick water would have been calm with 1 fine particles of mud slowly settling and forming layers that hardened I over many thousands of years. The .5 I I I I deposits change dramatically at the I I I I K-T boundary. Here, the K-T event I deposit is close to 1 meter thick and Om Tektite c::::)

consists of tektites and big chunks •••••• •• ••• Sandstone ..: - ..·:•:·:.... of rocks, including boulders. Boulders

. . • ' t . ~ ~,,,,.~ .~ ...· ,-::..,.. ~ ;r.-~~..,.,.. ·?-/-- -.r:,r- - ;...-,.. ..;....-<" ~ '!$,/ ,£ ~ ~ . .

K-T event deposits at this site

(Ph otos courtesy of Peter Schulte, Universitat Erlangen-Nurnberg.) HHMI HOWARD HUGHES MEDICAL INSTITUTE 5

At this site, the K-T ejecta layer is less 5 ., -;,,.}l!J: ., L::•~ • - I than 3 mm thick. The clay appears as I r . )- - , ' a dark, reddish layer. The ejecta con • • ' ' , I , 4 I I . ' sists of spherules, small shocked L f_ , · ~ ~ ' I ,..,3 mm thick I I - L-1 quartz grains, and Ni-rich spinels. . -. • 3 , s , ' ' - ,J. ' , The iridium concentration is one of . , I ~ ~ -;. - < ~ - 1 I I ''· . the highest among all K-T sites: , .. -,. , 56 2 - ppb. I I I I I 1 I I I I I I I I 0mm I Spherule 0 Shocked quartz D Ni-rich spinel ~ Clay ~

Mudstone ~

The clay layer contains spherules. Some appear white, while others • have been stained red by iron 25 µm oxides.

(Photos courtesy of Jan Smit, VU University Amsterdam.) HHMI HOWARD HUGHES MEDICAL INSTITUTE 6

5 - • I I I I I I I I 4 ■ .==a:=, I • I I

I I There are different types of impact • • • • F- ~ • • • evidence at this location. Spherules 3 I ' • • and shocked-quartz grains are abun , , ).. , ' • •~ ' . I Ejecta layer I I • • , L dant in the K-T ejecta layer. Iridium I r-r I , ' ' _, "\. , concentration is high, peaking at 2 ' , • • L , ' ' ~ '. about 20.8 ppb. • • • • •

1 I I I I I I I I I I 0cm I I Spherule 0 Shocked quartz D

Clay ~ Mudstone 0

Examples of spherules (left) and shocked quartz (right)

(P hotos courtesy of Jan Smit, VU University Amsterdam and United States Geological Survey (USGS).) HHMI HOWARD HUGHES MEDICAL INSTITUTE 7

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At this location, the K-T ejecta layer is less than 1 cm thick and contains 3 small spherules and Ni-rich spinels. < 1 cm thick Iridium concentration is about 18 ppb. 2 I I I 1 I I I I i I I I i i 0 Cm '----= = Spheru le 0 Ni-rich spinel -m Clay ~ 1 Mudstone t- 1 I

The site of the K-T boundary (designated by the red line)

(Photo courtesy of Jan Smit, VU University Amst erdam.) HHMI HOWARD HUGHES MEDICAL INSTITUTE 8

95 This site provides evidence from a deep sea core. The total length of the 100 cored section is about 260 meters and was recovered at almost 2.5 kilo 105 meters underwater. 110

Here the K-T layer is only a few milli 115 meters thick.

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One of the ships used in the Ocean Drilling Program Obtaining a deep sea core

(Photos courtesy of Brian Huber, Smithsonian Institution and William Crawford, Integrated Ocean Drilling Program.) HHMI HOWARD HUGHES MEDICAL INSTITUTE